I just looked up BrainExploder's video on the gun and the shooting performance was some of the worst I've seen - worse than a lot of cheap springers and LPEGs. After a burst of full auto he locked the bolt back, tipped the gun over and a shower of broken BB shards fell out where the bolt had eaten them.
Could be a lemon, but it seems like they haven't got the feeding right. Some GBBRs do the exact same thing and it's what happens when you try and use a firearm feed system on weak little bits of plastic. It takes a lot of refinement of the angles and forces to get it working spot on. The AAF has the best potential to come out the winner in the end to my mind, but it's year of development away from happening.