I bought a new IS2600Z last year and I'm running it for the first time now. I had a turf tirger (still have) . Scags dealer wouldn't budge on pricing. So, I went to Ferris Dealer and got a great deal on the Diesel. I think it's going to be harder to do maintenance on the Ferris but for the price difference, who cares. This Ferris is a lot faster then my Scags. Since I cut a lot of acreage it is important.
Diesel is the way to go, but be prepared to dig deep into your pockets. $$$$