ZTRs do not do well at all on slopes when there might be a little dew. When you lose rear traction, you also lose all steering. I know a guy who was mowing up close to a pond and the ground of course sloped towards the water. He hit a little wet spot with the rear wheel closest to the water and sideways he went, into the pond.
I agree. My Bad Boy ZTR is a bugger to run on a slope sideways. One lever all the way forward and the other back leaving a skid mark. Its ok though going up and down. Not sideways.