The best thing about Firefox is that if you delete it and then have to reinstall it, it stores all the old settings and extensions so that you don't lose your settings for ABP, TabMixPlus, or your history.
Yes, I have just had to discover this marvelous feature for myself. I was prepared to be full of WOE, and now I am full of JOY.
The only bad thing is that the session manager doesn't seem to save more than two sessions back, which sucks because there was an internets problem and my last session, which had nine or ten tabs open, got overwritten, and then someone else opened Firefox and now that previous-to-last session is gone! I can only vaguely recall what the tabs were were. Now I have to sort through my history to find out, because they were things I left open so I could back to read them. WOE.