Climbing slopes isn't too much of a problem either way. The trouble is going across slopes, along ditch banks, and down slopes, especially if the grass is a little damp. A standard ZTRs front end constantly tries to pivot to lower ground, so the uphill rear tire and the traction it can get is the only thing standing in its way.
My friend and neighbor across the street has an Exmark Lazer Z, so we tried it out on my property to see if I could buy a standard ZTR, but no dice. He owns a landscaping business and has plenty of experience, but there are many spots he wouldn't even attempt.
The long and short of it was I was going to have to push mow about 15% of my property with a ZTR, stay with a regular lawn tractor, or break the bank with an exotic commercial machine which made no sense for 2.5 acres. I could pay a lawn service for fifteen years before recouping the cost of some commercial mowers. Then the Z-Force S came out and I haven't had to use my push mower since. The best part is you can remove the deck and have a pretty sweet go kart. 9 MPH on my lawn feels like 90, especially when you get a nice four-point corner drift going. :biggrin: Seriously, the handling is insane.