Well, I can tell you that the Zero Effect makes no contact whatsoever with the shelf. Its not even close to making contact.One would need not worry about their arrow falling off this rest either with that hook arm.However, In my experiences I found this rest to be real finicky and difficult to tune. It was possible but took more time than I desired.

I just bought the Limb Driver and I feel safe in saying that it is the best rest I've ever used. I have mine resting over my shelf but it is about 1/8th " above the shelf. When it "drops" it drops to that position and does not hit the shelf. Also, it is the easiest rest to tune that I've ever owned. Another good thing is that it is not connected to your cables. So you don't have to worry about throwing your timing off either. Very well built rest.