The problem with saying they need something Chrome doesn't have is that a lot of others seem to expect them to have feature parity with Chrome, both in the GUI,

The problem with saying they need something Chrome doesn't have is that a lot of others seem to expect them to have feature parity with Chrome, both in the GUI, and in the backend rendering engine. I don't think it's economically feasible, it seems you can have one or the other but not both. Unless of course you're willing to outspend Google, which not even the very wealthy Microsoft wants to try to do (they dropped their own browsing engine and switched to Blink). To be clear what is on the table here: not keeping pace with Chrome means that some websites will just stop working in Firefox because some new web API is missing. So that's what you would be trading. I think the huge number of about:config options is actually a major problem for Firefox, there is no possible way to test all those options and ensure they stay working forever and have zero regressions. You won't like this, but a lot of them probably need to be removed. You would need to change the branding but I think some of the other Firefox modifications have systems in place to deal with that. If you ever need to do it, maybe it would be worth asking them.