Okay so I updated and I can indeed say that it is better. Here's some tips for those of you afraid.
1. Look for your disabled extensions directly at mozilla, they're prolly in beta, but most of them work.
2. Session Saver works. *G* It won't import your sessions though. But don't fear.
3. bleah.
4.
This version of TabMixPlus (scroll through) works FINE. AND it will import and convert the old session saver sessions into your new firefox.
5. I am without ljlogin or the other non greasemonkey LJ scripts. I am sad. I do not know my other passwords. Metafandom will be-- interesting.
6. The rest that's missing are minor bits, annoying to be without, but I suspect I can deal till they update.