Hey Frank. BC asked some pertinate questions ...I'l answer them for me. On the old tractor site I used to go to folks advised me against a zero turn because most of my yard is an old tomato field. Very very bumpy. The parts that aren't bumpy have hills. Nothing to serious, but they are hills.
I cannot mow at full speed across the bumps or it jars my teeth and back pretty bad. But varying speed is simple with a ZTR so going slower over those areas is a breeze. It also handles my hills with no problem, as long as they are dry. If wet, stay off the hills.

I have seen ZTR on landscapers trailers with a R4 type of tread instead of turf tread like most ZTR's come with. IOW, even if you have serious hills, there are ways to make the ZTR handle them.
I didn't have to many obstructions before getting the Zero Turn but since getting it I have not hesitated to add trees or whatnot in the yard. Before, when mowing with the Kubota using a 6' 3PH pull behind I cringed at the mention of adding new landscaping tot he yard. Now I welcome it.
Mowing is actually fun, or as fun as mowing can be. I always where shades or clear safety glasses when I mow now because with the ZTR a quick turn can end up putting grass and dust in your face. Much more than sitting high up on the Kubota. No biggie, just something to be aware of.
I love the Scag. I shoppped and shopped before buying it. I was leaning to an Exmark but when I found there were no local dealers I looked hard at the Scag and other offerings in the market. I like how rugged Scag was built. It was far from the cheapest but I was buyin a 10 year mower, like you plan to do. I'm at 5 years in and I'm sure I'll get more than 10 years out of it. 15 or 20 seem reasonable, but I don't put 200 hours on it a year. I'm more like 100 hours.
The gas engine has plenty of power, so from that angle I think the Scag would do you fine. At 200 hours a year, where the diesel would pay off is longevity. At the time I bought I also dreweled over the Kubota diesel. Very nice ZTR. The price difference between the gas powered Kubota and the deisel power Kubota was 3k. I could not justify that difference, and if I were buying new again today, I would make the same decision and buy the Scag Wildcat (it was listed at 8500 marked down to 7500 when I bought it). The Wildcat is more of a commercial mower, a middle of the line offering 1500 or so more than the Tigercat Scag.
If you have any other questions just fire away Frank.
