I don't see in either incident where the starting bench was the problem. In the first incident the operator put his hand to the prop to reach for something... This could have happened just the same on the ground for the same operator. In the second, the prop came off... The operator did not check the prop in pre-flight. If on the ground, the prop most likely would have bounced just the same. At my field the pits are paved, a wood bench would absorb more than pavement in this case. I think blaming the bench will solve nothing, and not using them opens up to many other potential hazards.