IMO Black Edition is the only one worth getting. Silver is the same as the Hero 2 just smaller/lighter. If you want the silver you can prob just find a Hero 2 for real cheap now.
Black Edition can record:
720p at 120fps
1080p at 60fps
2.7k at 30fps
720p at 60fps
1080p at 30fps (30fps is pretty useless in recording anything with motion in my experience)
And the Black Edition comes with the Wifi remote which is $80 itself so that alone makes it worth getting for.