For whatever it's worth as a non-developer, I really like this. I think it's good to get some btrfs stuff implemented now so that Fedora is ready to fully utilize it whenever it's marked stable.
You mentioned that it would rollback user's home directories if they were btrfs as well. I have two questions about that. One, would it be possible/practical to default to a seperate /home volume for btrfs installations and, two, if it's on a seperate partition, but is also btrfs, would it still roll-back? IMO, it should be implemented so that it doesn't, but your feature proposal makes it sound like it would. - eqisow