There is no question you should go with the gas 825 over the diesel in this case. I have had both and have had probably the best true utility UTV for off-roading currently made, the Polaris 800 EPS LE (of course any of these would not compete v. a 400 pound bed capacity sport UV) but I am talking true UV. My Polaris would be a little faster in the woods and on trails than my Gator would be due mainly to its power steering, slightly smaller physical size and lighter weight. Not all Rangers have power steering, but mine did. The diesel Gator is a great work machine with a good deal of torque. It is heavy, but accelerates well. Unfortunately, it simply lacks the horsepower to keep up with either JD's own 825i or the Polaris in top speed, acceleration or off-road environments, though I found it to be a good off-roader, particularly in slow speed maneuvers. The 825 give one the best of both worlds. Though its gasoline engine likely would not last as long as the diesel in the 855, it is a true automotive style powerplant and is heavy and well-made. It has excellent torque and would likely last thousands of hours before needing replacement at which point the machine likely would have been sold or totaled already. This machine would give the Ranger a run for its money in almost every off road situation and is a much better work machine and pulling machine than the Ranger. The difference here is pretty noticeable, making it a better choice for plowing snow, pulling carts and trailers, hauling heavy loads, etc. My opinion is if you are looking at JD products and are interested in working the machine hard but keeping up with your buddies on the trail, the 825i is the way to go. In all honesty, and this coming from someone who likes diesels in these machines, I would not go diesel at all in this choice unless one has a dedicated fuel supply on a farm or something that would make diesel more convenient to own for that reason. Does this help??
John M