I would agree if some one is using a hydraulic press, maybe even a modified spring. But with a lever I guess maybe I am missing something. i mean the weight on the puleys should still only be a couple dozen pounds, so other then the arm or foot snapping (which could spit shards I guess) the only other issue I can think of is wrecking your table or chipping your floor if the weiths drop.
I am not encouraging people to just make random mods, and I would recommend think through what you are doing, and ask if you dont know.