TL;DR: I second your points and add some anecdotes of my own. Like you say, Noodlers inks have various flavors of permanence, from none, to archival / eternal,

TL;DR: I second your points and add some anecdotes of my own. Like you say, Noodlers inks have various flavors of permanence, from none, to archival / eternal, bulletproof, and Wardens series. Almost all of them are PH neutral which helps keep them from harming the pen they are in or more commonly the paper they're put on. I treat inks at my house on a spectrum, depending on how long I want whatever I'm writing to last. 0. Goners - chucked because they couldn't even hit level 1. 1. Non-permanent - often water soluble, looks great and behaves well, but I don't expect it to survive being in the sun, getting wet, or otherwise taking any torture at all. An example of this is Diamine Red Dragon, which has a cool name and a cooler look on paper. 2. Bulletproof - my standard inks for journalling or other documents that I want to resist aging and be reasonably readable if dunked in a bucket of water. An example would be Noodler's Heart of Darkness (looks like a shiny onyx black on paper) or Noodler's Navajo Turquoise (optional Eel), or even the humble Noodler's Bulletproof Black (looks like a grainy black). 3. Safe inks - My 'nice' non-permanent inks. Used for birthday cards, special occasions, and self-indulgent musings if the writing is not intended to be used more than a year or so. I also reach for these when I have a pen that is misbehaving with my usual inks. An example of this would be Pilot Iroshizuku Iro Ai. 4. Top Security inks - There are only 2 of these in my house. Noodler's Bad Blue Heron, and Noodler's Bad Belted Kingfisher. I use the latter in my Myu 701 for things that I want to last till the end of time, and resist the sun, rain, bleach, forgery lasers, the works. None of the above considerations can be applied to ballpoint or rollerball pens, indeed, you are lucky if you have a 3 color pack of something nice from the disposables, like the Uni-Ball Signo DX UM-151 if you are gonna go to JetPens, otherwise you are stuck with the Uni-Ball Vision Elite Needle Grip family, which does okay, but still doesn't hold up to all the color varieties, nib variations, and grip sizes that fountain pens offer. When I need to reach for a pen that is not a fountain pen for whatever reason (half the time all my FPs are just clean and un-inked and/or out of ink and I don't have time to fill 'em) I reach for the Pilot Hi-Techpoint V7, which is a refillable version of the Pilot Precise series of pens.