I would love to add my two cents here. I think if you are shooting correctly with your back, it is almost impossible not to have a hand that moves back on release. One must clarify though that the hand moving back is a result of the string being gone! You dont move your hand back to release the string! At the moment of release I like to be in a very comfortable yet stable full draw where the push of the bow is cancelled by the pull of the back. If you get a clean release(which with proper backtension is made fairly obtainable), your drawing hand will move backwards every time. In my opinion(not sure what its worth), the back is the most overlooked tool to great shooting.