My neighbor has a zero trun mower and he can cut grass faster than I can walk, and I can walk pretty fast. As long as the grass is not too high you can really go on a ZTR. In Florida you can't be in the lawn business without one. Most people who want to be competative use a "Dixie Chopper" brand. They come with comparatively huge engines(up to 40hp), you can get then with kubota diesels if you choose. They can easily cost 10k in a good market, but they cut 74" wide and they say you will cut 8.9 acres an hour.
I personnally would want a liitle more versatility if I were to spend that much money, so a compact tractor makes more sense to me. I might spend a little more time mowing but you can't hook a boxblade to your ZTR:wink:.