I would get a steering wheel ZTR. I have one, and I got it because they were supposedly better on slopes & hills. They absolutely are. I still have a lap-bar ZTR, and it doesn't hold a candle to the steering wheel machine on slopes & hills. Unfortunately, Cub Cadet is the only mfr making them. Zero turns have a lower COG than a typical lawn tractor, but since the front wheels behave like casters, they don't perform well on slopes. And the rear diff is open, so the uphill wheel will tend to spin. A steering wheel ZTR solves all that. To get better than a steering wheel, ZTR for hills & slopes, you'd need to move up to something like a Ventrac. BTW, my SW ZTR is rated for slopes up to 20 deg.