I think you will happy with a 3000 series and how it mows. They are large machines, but maneuver well for their size. With turf tires, even loaded, they will not damage your grass. It is true that a ZTR will cut your acreage faster, but your proposed machine will be quite fast and should be able to mow about 2-2.5 acres per hour if the grass is not too heavy, plus you can do other things with it. All things equal the 3000 series also should have about twice-three times the engine lifespan of a high-end gas powered ZTR, and probably 20% longer than a diesel-powered one, though this of course would be variable. I have had both machines and prefer the tractor-style by a slight amount, though I enjoyed my last JD 950 ZTR. I do not think you can go wrong here.
John M