In 2000 hours, the diesel would burn about 1/3 less fuel more than paying off the cost difference of the diesel engine. Its effectively 'free' over the life the machine, and gives much better torque which is very noticeable on a ZTR.
Absolutely.
I have a Grasshopper front mount (Kubota diesel engine). I tested several brands of ZTRs and for my property, the GH diesel front mount was like a match made in heaven. No other mower came close. But my property has a lot of trees, some steep areas, rolling twisting areas, dips, and swales. All the gas ZTRs I tested had problems holding speed on the long inclines and crossing the dips and undulations at an angle without scalping, until I tried the diesel GH with the front mount deck. Like I said, it was a perfect fit for my property. That diesel lets me mow lanes and rough areas I used to bush hog too. I cut my mowing time in half or less. I plan to add a second GH diesel soon to replace the JD gaser my son uses to mow. Bottom line, try several brands if you can... especially if your property isn't flat and easy. There are a lot of quality brands, so dealer support should also influence your purchase.
Are you saying it has a front mounted deck like the Kubota F models?
The Kubota F series does have a front mounted deck, but that's about the only thing in common with the Grasshopper front mounts. The GH are zero turn mowers and much more flexible in applications than the Kubota front mounts. I'm not trying to compare the GH to Kubota here. My point is this... When I was looking for a mower I eventually had it narrowed down to Kubota and Scag. While researching and test driving those final models, the Kubota dealer recommended GH over Kubota. As they put it, GH is the best mower design out there, and uses the best diesel engine available (Kubota). They sell several brands including Kubota and GH. So I test drove GH and realized there was a huge difference, and that the GH fit my needs perfectly. Unfortunately for that dealer, he was not the strongest for service and support (in my mind). So I found another GH dealer closer to me who provides much better service. Bought my GH from him, and I'll be buying a second one from him soon. So, shop around. There are a lot of choices, and some very good dealers who you will be working with for years to come.
Have you tried a Ventrac?
That's what I have in mine, I wanted a steering wheel instead of handles.