Minefield isn't the next Firefox, it's just the name the Mozilla devs give to the latest nightly build...because it's so buggy as to be a minefield.
The speed of the new Firefox 3.1 beta is down to the Trace Monkey engine, I believe.
I use FF for my general browsing, but I can't beat Chrome for its handling of GMail, GCal, GReader, GMaps et al. I'll be looking at FF3.1 when it is released.
A great deal of the knee-jerk reactions over the EULA for Chrome was down to a lazy 'cut and paste'. A number of third party tools exist to disable the opt-in usage tracking.