I made the switch. I want to say its glorious, but there are definitely some pain points. Not with Firefox itself, mind you (it's seriously amazing), but with 3rd party apps. Things that I use every day _suck_ on Firefox. Top of the list right now is Lastpass, which while completely seemless on Chrome, doesn't even have the ability to copy a username or password on Firefox (what??) (anyone have a two-factor auth alternative?).
Still, they really nailed it with quantum. The dev tools are excellent (finally!). I can deal with the second rate extensions if it means compartmentalizing just a small slice of my life from Google.
When I switched to Firefox I also switched to bitwarden for password management. Auto-filling is still in beta but I don't miss it. The Firefox extension is fast and simple to use.
I use the built in auto fill with Kee (for KeePass). It works great, my password manager types my passwords in initially and Firefox stores and syncs them across devices with reliable auto fill.
Still, they really nailed it with quantum. The dev tools are excellent (finally!). I can deal with the second rate extensions if it means compartmentalizing just a small slice of my life from Google.