Earlier quoted context omitted.
Game changer! Now from my POV Firefox is the best desktop browser, period. No caveats.
Is there a good transition path for someone who uses a lot of Google products? In particular, I use Chrome across all my devices, and I depend on the ability to search my history/recent tabs/etc from anywhere. Will Firefox give me the same ability? Is the transition literally just: Install Firefox everywhere and start using it instead?
Yep. I did this about a year ago. You have to create a Mozilla account (if you haven't already) in order to sync your tabs and history across devices, but that should be a given.
I find the Firefox sync a bit clunky compared to Chromes though. I think Chrome sends udpates to Google on each change whereas Firefox polls and updates on a schedule which means sometimes if you put a device to sleep (or if you're on iOS and the app gets suspended) your history and tab state won't be propagated and it'll be missing on your other devices which can be frustrating when you're away from those devices.