Which version of Firefox should you try? Stick to the most stable version you feel comfortable with, although the temptation to sneek a peek ahead is actually quite compelling with these latest developmental builds. - LANjackal from Bookmarklet
I've been using Firefox 11 at work and I have to admit that I really like it. I still use Chrome for day-to-day browsing but for development? Firefox wins (for now). - Akiva