I know this is the Kubota forum, and a lot of these comments are in jest, but since you guys are all over the place anyway-
I bought a Cub Cadet Pro Z 972SD a few months back and have seriously been impressed. It'll mow sideways on slopes that I previously only mowed straight up/down with a 75HP 10K pound MFWD tractor.
Manufacturer's literature shows it'll mow 25 degree slopes, but I'd be willing to bet that's conservative. And with a 35HP Kawasaki motor, I can't bog it down. I will say, it's thirsty though.
I only put about 10 hours on it this fall before weather turned cold and the grass quit growing, but so far so good.