Been there, done (doing) that, for quite a while now...
The 64 bit version is all I've been using for many months. All the way from the 4bpre to the latest 8bpre.
Works a treat. Especially with the latest Flash "square" 64 bit preview.
I don't even have the 32 bit versions of FF installed anymore.
BTW, shouldn't this be in the "Browsers" section of the forum?
I only mention such because the last time I presented such as "news" it got kicked there. Sorry, JMH, nothing personal, just an observation.