I've never been quite happy with a traditional lawn tractor on a hillside. I loose traction frequently (4x4 would be nice), but also part of the reason I loose traction is when going cross slope, the lawn tractor gets much lighter on the uphill wheel, which then spins, and without a locking differential, one doesn't go anywhere.
Anyway, I've always thought the zero-turn mowers looked like they would be much more stable on hillsides, but I haven't had a chance to try one out. 4x4 with a limited slip differential would still be nice.
