Yuup. Latency is a huge issue for Git. Even hosting Git at non-trivial scales on EBS is a challenge. S3 for individual objects is going to take forever to do even the simplest operations.
And considering the usual compressed size of commits and many text files, you're going to have more HTTP header traffic than actual data if you want to do something like a rev-list.
And considering the usual compressed size of commits and many text files, you're going to have more HTTP header traffic than actual data if you want to do something like a rev-list.