While its not great on the valves, I can also assume you (him, whoever) won't be using it 24/7.
I use a 2-step to drag race and can safely guesstimate that I have at least 150 drag passes all using the 2-step and I've yet to have a failure (on all stock internals)
I wouldn't hesitate to set it up, however for stuff like roll racing I've always been a fan of simply manipulating the gearing to get the car moving (spooled)