I like the idea of reverse rotation. My worry is the rocks will get jammed in the machine between the tines and top cover? If it only "herds" the rocks, I live with that!
On occasion, a larger rock (softball size to grapefruit size) can jam between a tine and the housing, especially on the smaller diameter one like mine. Larger rocks than that usually won't jam, and smaller ones just pass through. One of the full-size diameter tillers probably won't do that; a rock big enough to jam one of them won't get lifted high enough.
When I do get a rock jam up, the slip clutch protects my driveline just as it should, but it is easy to un-jam. The procedure I found to work very well is to 1- stop the PTO (obviously!!!),2- lift the tiller to full lift height, then 3- disengage the rear PTO by moving the lever to the mid-only setting, so the rear PTO shaft can free-wheel. Shut off the engine for ultimate safety, then 4-rotate the tine shaft forward manually and the rock will drop free. Sometimes, as soon as you disengage the PTO, the rock will drop free.
In tilling an area, the more times it is tilled, the less rocks big enough to cause problems there will be. Over a couple of gardening seasons, you'll have most of the biggest rocks cleared out. It's worth having to stop a few times to clear a rock, the quality of till is amazing with reverse rotation, the ground is well pulverized. It is always best to plow before tilling, that will bring up some rocks that can be cleared before you till, to minimize issues later. The broken ground also breaks up and pulverizes more easily than trying to till unbroken ground.
