I actually have been using Fennec/Firefox for a couple of weeks exclusively, mostly because I've gotten so used to the various finger-gestures to call up the awesome bar/back-forward buttons/tabs, etc. I love the add ons and the possibilities are great. I also think the bookmark implementation is better (and easier to manage, thanks to Weave). But reading this thread made me hop back onto MicroB and it's just so much smoooother I may have to switch back... That said, MicroB does seem to crash more often - I've rarely had that problem with Firefox.