I think the AFG2 is slightly smaller, and doesn't have the "wings" that go up the side slightly that may interfere with stuff mounted on the side. If you have a lot of stuff hanging all over your rails the AFG2 might be the way to go.
I ordered a black AFG 2 from BCM yesterday. I ordered immediately after receiving notification they were back im stock. Anyone looking for one may want to check there.
My AFG1 is now on my 15/22 and the AFG 2 is going on my BCM middy.