zero turn for sloping land

I've been told that a zero turn with steering wheel is the best mower for sloping land. A neighbors lawn service owner has commercial grade cub cadets, but says that if Toro made a commercial zero turn with wheel, he would buy it in a heart beat. His cubs are in the shop quite often. I have a 15 year old cub lawn tractor, 42" that has served me well, but is not enough for my 6 acres of mowing, much of it on a gentle slope. S o the question is: would the Toro homeowner grade work well for me or would I be better off with a commercial cub. I can't see beating my machine up like a business owner would.