I kinda hope being that I bought my S3 outright, completely devoid of any carrier that it'll arrive fairly soon, vs carrier branded ones. Interestingly enough, my S3 is quite a margin quicker than my friends 3UK branded S3.
As for the flash, just backup the APK using Titanium Backup, and then install it on JB later.
It's not supported, that doesn't mean it wont work. Also, it's already mentioned that flash is turd, slow, buggy and a miserable battery hog, Apple actually got something right!