I imagine it would work but I wouldn't want to be standing near the valve to operate my Shaver post pounder when it strikes the wood as I'm sure pieces will go flying with force. The other worry is mine doesn't have alot of force going up so if your wedge gets stuck you will possibly not have the pounder pull the wedge out and quite possibly you would just pick the piece of wood up with the wedge stuck in it.
But I could be wrong and the whole idea might work quite well, but i still wouldn't want to be standing next to it operating the valve.