Hi guys, I'm a n00b here, but I'm so happy that I just had to share my experiences. I have 5 acres of mostly hilly land with a rather large hill beside the house (I have an odd lawn layout). Had been using a 1980-something (I think) Cub Cadet 1200 that was my grandfather's. I had been looking a getting a new mower on and off for a few years, and got real close to purchasing a JD CUT, but then I reconsidered and ended up not buying. Another year passed and I was looking at ZTRs, but was concerned about putting one on my hilly land. I went to my local Toro dealer that I had taken the Cub to for some minor fixing and had him bring one up for a test run. I had no problems what-so-ever so I took a plunge and bought a brand new (0.5 hours) Toro Z500 52" for $6700 (with ROPS). I have used it a couple times since I bought and haven't had any trouble mowing the hill. I couldn't be happier. 
So to anyone thinking about ZTRs on rather steep inclines, give them a try and I think you'll be surprised.
So to anyone thinking about ZTRs on rather steep inclines, give them a try and I think you'll be surprised.