FireFox developers really missed the boat on this one!
I liked some of the changes, especially the sync feature in 4 but within about 2 hours of install ff4 allowed something in and right past av (not that I'm happy with that as either) so I went back to chrome, ff 6 seemed better but still haven't gotten over my experience with ff 4.
Ironically it would have been solved by a noscript switch but it was new enough to not have one yet. Or at least not one I could find at the time.