I (re)installed Mozilla today in order to try out Epiphany, since Epiphany uses Mozilla's rendering engine. After checking out Epiphany -- it's OK but doesn't have that much flexibility -- I did a bit of browsing with Mozilla; I have to say, its rendering is definitely faster than that of Firefox (BTW, Firefox 1.0.2 is out).
If it weren't for Adblock, Gmail Notifier and other goodies, I would definitely make Mozilla my primary browser.