My only worry about sticking to the old tried-&-true's (about which I agree: I hate all this constant changing) (especially when it disables Zone Alarm) but I'd be worried about security flaws in the past versions. Firefox (and Adobe Reader and every other widely popular app/site) is a magnet for hackers seeking to exploit any flaw they can find, and they've had a lot of time to manipulate the weaknesses in the old FF; so I suppose this is as much about keeping a step ahead of them as anything else. It's still a drag, tho...