My tiller seems to put less stress on the tractor than pulling a box blade. I have my skid shoes set at 2". The Bota can chug along at 1/2 throttle and barely notices the drain from the tiller.
When I have the shoes set all the way for depth, the angle of attack on the soil is severe, so the tiller bangs and bounces and hammers. With the shallow cut, the blades slice through the soil and it is smooth as silk.
With multiple passes, the skid shoes are 2" deep plus the depth of the previous cut, so it goes down with multiple passes.
I would not be afraid of the larger tiller, assuming your 3PH can lift it ok.
One consideration is if you have rocks, to see if it has a slip clutch. Mine does and it is nice when it grabs a rock or root. I'd price a local new unit set up with a clutch, and figure your auction price as a percentage of that.
Ron
