> people think that a new release is dangerous and is going to break something, but backported fixes by people who aren't as familiar with the codebase make it perfectly safe
Pentadactyl consistently breaks every six weeks, leaving Firefox in a nearly unusable state. Since I switched from the addons.mozilla.org version to the mercurial, it stopped happening for a while, but just the other day it happened again with Firefox 21.
So, people have reason to fear the constant upgrading. It's unfortunate that security takes a hit when you avoid doing it, but doesn't matter how secure a browser is if nobody can use it. wget is more secure than Firefox, and probably I could carefully construct POST data and post to LWN using it, but still I choose Firefox every time. The same logic goes for using old Firefox versus new Firefox.