Have no experience with the Kubota UTV's. Really wanted a diesel one, but settled for Kawasaki 610 Mule. For our use the gasser made better sense. Only have about 5 acres. Lots of engine start/stop with yard work, moving stuff between garages, etc. Its no speed demon, but one tough little machine. Besides, any more than 20 mph it will bounce your BB's off.
Retro fitted it for garden tractor size battery for economics. Those ATV batteries are not cheap and only last 2-3 years. The garden battery is going on 5 years now. Plus I use a tank sprayer, so having that reserve power is nice.