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A friend of mine told me earlier today that they had a discussion at work (a coding shop) about "downgrading" to luna from sol for cost reasons and that many we

A friend of mine told me earlier today that they had a discussion at work (a coding shop) about "downgrading" to luna from sol for cost reasons and that many were quite unhappy about this because they didn't want inferior tech to be forced upon them. Do they have a point? Is sol actually worth the extra cost? Especially if you ramp up the effort level?

dude250711 1mo ago
Yes. If they don't like the cost then they should fire the "leader" who introduced the AI there to begin with.
pseudosavant 1mo ago
It is a good question. Luna is definitely a very capable model. Much more capable than the top SOTA models from 12 months ago. It definitely isn't at the same level as Sol, but you get 20x the tokens for the cost, and it has a much faster tokens/second rate. If this is a cost conscious company where I'm going to get a fairly limited amount of Sol, or a nearly unlimited amount of Luna, I'm probably choosing Luna.
- ImaCake 1mo ago
  Luna on xhigh unlocks gh copilot for me. Sol, even discounted, is too expensive to use and is much slower. Luna on the other hand seems to be so cheap you don't have to think about cost.
- deaux 1mo ago
  > Much more capable than the top SOTA models from 12 months Confidently wrong here. It's absolutely not across the board "more capable" than GPT 5 or Opus 4.1 or even Gemini 2.5 Pro. It's potentially better at certain specific tasks, mostly agentic coding implementation work. I.e. tool calling and usage of bash. It's worse at a large range of other tasks.
usef- 1mo ago
Luna as a doer, with a smarter model planning, can be a good compromise. Using sol for everything can be expensive without much gain, as a lot of steps don't need that sort of intelligence.
- praveer13 1mo ago
  Luna is great at doing targeted smaller work, I use sol max for creating a plan and targeted /goal prompts after I finalize the design. Or Claude with ultracode for design and planning and adversarial review by sol max and then delegate to Luna for smaller goal prompts
kingstnap 1mo ago
Smaller models + more effort has strong diminishing returns, especially if your goal is to save money. Sol already lacks judgement. It will absolutely add idiotic tests and comments. Luna is that but worse so if you account for things like going down wrong paths, producing bad results, overthinking then it could easily cost you more to get less.
bunderbunder 1mo ago
I don’t love the “forced upon them” framing; if that’s really how people are thinking about it then maybe they should pause and reflect for a moment yhat it isn’t their money being spent. Amd the default isn’t always having the latest and greatest, it’s not paying for anything at all. Now, if the debate is really about which option is more cost effective, then we could easily run an A/B test to find out. Though TBH my instinct is that that experiment is likely to cost more than the potential cost savings. What I will say is that my own sense from experimenting around in a non-rigorous way is that the answer depends on how you use the tool. For actual vibecoding you should always go for the SOTA model because it will need less oversight. It’s also less likely to get stuck in a vicious loop that fruitlessly wastes tokens. But for a more hands-on approach where you move in small, carefully planned increments that you review and test in human-comprehensible chunks, smaller models may be preferable. SOTA ones don’t do that much better when working that way, and the slower inference adds a detrimental amount of friction to the work cycle.
- abustamam 1mo ago
  I recently just had fable run itself into a loop. Im sure it would have stopped itself at some point (perhaps when i ran our of tokens?) But I still stopped it early when I noticed it trying to get something to work when the solution was in a file in a sibling repo.
- teiferer 1mo ago
  > we could easily run an A/B test I'd object to "easily". It's already hard to measure whether AI is generally worth the cost. Let alone compare models in such detailled ways. It's mostly handwaving and gut feeling Doesn't mean the conclusions are wrong, but biases are strong.
azuanrb 1mo ago
I’m building an internal tool for our company, basically an agent to help with on-call and alerts via Slack. I have evals running across a few scenarios, and my favorite models so far are Sol medium and Luna xhigh. Sol medium has been a nice balance between intelligence and response time. Luna xhigh can achieve similar scores on the evals, but it takes noticeably longer. My impression is that the higher reasoning effort helps compensate for the lower base intelligence. Cost is definitely a big factor, but latency and intelligence matter too. If I had the budget, I’d take Sol medium over Luna xhigh. From using both on real scenarios, Sol is noticeably better at navigating around issues, exploring alternatives, and being creative when the obvious approach doesn’t work. That matters quite a bit when you’re investigating live alerts, where the path to the root cause isn’t always straightforward.
brikym 1mo ago
It's silly to discuss it. Just do the evals.
noodletheworld 1mo ago
Is sol better? Yes. Categorically. Anyone who tells you otherwise and that luna is “just as good” does not know what they are talking about. Going from sol to luna is a downgrade. It is not a question, it is a fact. > Is sol actually worth the extra cost? Is a question only you can answer, because it has no generic answer. Right now, for me, being able to use sol is worth the cost, but using it all the time is not. I’m sure going from using it to using luna feels rubbish; but there are realities about costs you have to face sooner or later. Maybe like… give your team credits and make them pick the right tool for the job; and if they burn their credits on sol in 20 minutes, well, tough luck buddy, looks like you're coding by hand for the rest of the month. Team will quickly shift. People hate losing access to ai.
- vatsachak 1mo ago
  Idk... Luna is great if you generate specs before implementation. Sure a Lexus is better than a used Prius, until you include price
  - noodletheworld 1mo ago
    Anyone who can’t tell the difference between driving those two cars isn't actually driving. You cant just go “oh hey, I guess they're both cars so I’m taking your lexus away, catch a cab its cheaper” and expect people to just hug you be be like “yay, thanks! I still have a job I guess! :party:” :P
    - defrost 1mo ago
      Straw argument. Obvious to the meanest intellect they can tell the difference between the cars.
      - noodletheworld 1mo ago
        So can anyone using sol and luna. Don't complain to me if someone responds using a stupid metaphor that proves the opposite of the point they were trying to make.
shepherdjerred 1mo ago
I choose to use Luna for most tasks because it is cost efficient, even though I get a pretty generous budget from my company. Sometimes I will use Fable or Sol for large features/projects, or research/exploration. I would not be at all happy if I were forced to use Luna, though. I’d probably start looking to leave. I don’t want to work somewhere where I don’t have choice over my tools.
- teiferer 1mo ago
  > I don’t want to work somewhere where I don’t have choice over my tools. As long as there is no cost involved there is little reason to restrict such tooling, but expecting your employer pays non-trivial sums is likely to raise questions about whether that extra cost is worth it. In this case, is the delta from luna to sol worth the extra order of magnitude in cost. If it's $2 a day vs $20 a day then there should be little discussion, but at $50 a day vs $500 a day, the question seems relevant.
  - shepherdjerred 1mo ago
    It's reasonable for a company to not want to burn money. It is not reasonable for a company to pay a fully loaded engineer >$40k/mo and then ask them "why did you need $500?" on some odd days where they are doing difficult work, large refactors, experiments, etc.
DarmokTanagra 1mo ago
They should try "downgrading" to people who don't need a random number generator to do their job for them.

dude250711 1mo ago

Yes. If they don't like the cost then they should fire the "leader" who introduced the AI there to begin with.

pseudosavant 1mo ago

It is a good question. Luna is definitely a very capable model. Much more capable than the top SOTA models from 12 months ago. It definitely isn't at the same level as Sol, but you get 20x the tokens for the cost, and it has a much faster tokens/second rate. If this is a cost conscious company where I'm going to get a fairly limited amount of Sol, or a nearly unlimited amount of Luna, I'm probably choosing Luna.

ImaCake 1mo ago
Luna on xhigh unlocks gh copilot for me. Sol, even discounted, is too expensive to use and is much slower. Luna on the other hand seems to be so cheap you don't have to think about cost.
deaux 1mo ago
> Much more capable than the top SOTA models from 12 months Confidently wrong here. It's absolutely not across the board "more capable" than GPT 5 or Opus 4.1 or even Gemini 2.5 Pro. It's potentially better at certain specific tasks, mostly agentic coding implementation work. I.e. tool calling and usage of bash. It's worse at a large range of other tasks.

usef- 1mo ago

Luna as a doer, with a smarter model planning, can be a good compromise. Using sol for everything can be expensive without much gain, as a lot of steps don't need that sort of intelligence.

praveer13 1mo ago
Luna is great at doing targeted smaller work, I use sol max for creating a plan and targeted /goal prompts after I finalize the design. Or Claude with ultracode for design and planning and adversarial review by sol max and then delegate to Luna for smaller goal prompts

kingstnap 1mo ago

Smaller models + more effort has strong diminishing returns, especially if your goal is to save money. Sol already lacks judgement. It will absolutely add idiotic tests and comments. Luna is that but worse so if you account for things like going down wrong paths, producing bad results, overthinking then it could easily cost you more to get less.

bunderbunder 1mo ago

I don’t love the “forced upon them” framing; if that’s really how people are thinking about it then maybe they should pause and reflect for a moment yhat it isn’t their money being spent. Amd the default isn’t always having the latest and greatest, it’s not paying for anything at all. Now, if the debate is really about which option is more cost effective, then we could easily run an A/B test to find out. Though TBH my instinct is that that experiment is likely to cost more than the potential cost savings. What I will say is that my own sense from experimenting around in a non-rigorous way is that the answer depends on how you use the tool. For actual vibecoding you should always go for the SOTA model because it will need less oversight. It’s also less likely to get stuck in a vicious loop that fruitlessly wastes tokens. But for a more hands-on approach where you move in small, carefully planned increments that you review and test in human-comprehensible chunks, smaller models may be preferable. SOTA ones don’t do that much better when working that way, and the slower inference adds a detrimental amount of friction to the work cycle.

abustamam 1mo ago
I recently just had fable run itself into a loop. Im sure it would have stopped itself at some point (perhaps when i ran our of tokens?) But I still stopped it early when I noticed it trying to get something to work when the solution was in a file in a sibling repo.
teiferer 1mo ago
> we could easily run an A/B test I'd object to "easily". It's already hard to measure whether AI is generally worth the cost. Let alone compare models in such detailled ways. It's mostly handwaving and gut feeling Doesn't mean the conclusions are wrong, but biases are strong.

azuanrb 1mo ago

I’m building an internal tool for our company, basically an agent to help with on-call and alerts via Slack. I have evals running across a few scenarios, and my favorite models so far are Sol medium and Luna xhigh. Sol medium has been a nice balance between intelligence and response time. Luna xhigh can achieve similar scores on the evals, but it takes noticeably longer. My impression is that the higher reasoning effort helps compensate for the lower base intelligence. Cost is definitely a big factor, but latency and intelligence matter too. If I had the budget, I’d take Sol medium over Luna xhigh. From using both on real scenarios, Sol is noticeably better at navigating around issues, exploring alternatives, and being creative when the obvious approach doesn’t work. That matters quite a bit when you’re investigating live alerts, where the path to the root cause isn’t always straightforward.

brikym 1mo ago

It's silly to discuss it. Just do the evals.

noodletheworld 1mo ago

Is sol better? Yes. Categorically. Anyone who tells you otherwise and that luna is “just as good” does not know what they are talking about. Going from sol to luna is a downgrade. It is not a question, it is a fact. > Is sol actually worth the extra cost? Is a question only you can answer, because it has no generic answer. Right now, for me, being able to use sol is worth the cost, but using it all the time is not. I’m sure going from using it to using luna feels rubbish; but there are realities about costs you have to face sooner or later. Maybe like… give your team credits and make them pick the right tool for the job; and if they burn their credits on sol in 20 minutes, well, tough luck buddy, looks like you're coding by hand for the rest of the month. Team will quickly shift. People hate losing access to ai.

vatsachak 1mo ago
Idk... Luna is great if you generate specs before implementation. Sure a Lexus is better than a used Prius, until you include price
- noodletheworld 1mo ago
  Anyone who can’t tell the difference between driving those two cars isn't actually driving. You cant just go “oh hey, I guess they're both cars so I’m taking your lexus away, catch a cab its cheaper” and expect people to just hug you be be like “yay, thanks! I still have a job I guess! :party:” :P
  - defrost 1mo ago
    Straw argument. Obvious to the meanest intellect they can tell the difference between the cars.
    - noodletheworld 1mo ago
      So can anyone using sol and luna. Don't complain to me if someone responds using a stupid metaphor that proves the opposite of the point they were trying to make.

shepherdjerred 1mo ago

I choose to use Luna for most tasks because it is cost efficient, even though I get a pretty generous budget from my company. Sometimes I will use Fable or Sol for large features/projects, or research/exploration. I would not be at all happy if I were forced to use Luna, though. I’d probably start looking to leave. I don’t want to work somewhere where I don’t have choice over my tools.

teiferer 1mo ago
> I don’t want to work somewhere where I don’t have choice over my tools. As long as there is no cost involved there is little reason to restrict such tooling, but expecting your employer pays non-trivial sums is likely to raise questions about whether that extra cost is worth it. In this case, is the delta from luna to sol worth the extra order of magnitude in cost. If it's $2 a day vs $20 a day then there should be little discussion, but at $50 a day vs $500 a day, the question seems relevant.
- shepherdjerred 1mo ago
  It's reasonable for a company to not want to burn money. It is not reasonable for a company to pay a fully loaded engineer >$40k/mo and then ask them "why did you need $500?" on some odd days where they are doing difficult work, large refactors, experiments, etc.

DarmokTanagra 1mo ago

They should try "downgrading" to people who don't need a random number generator to do their job for them.