We have 6+ acres to mow weekly. Hundreds of trees to go around and most is somewhat bumpy. Pretty much set on a Ferris brand ZTR. Suspension really allows us to max out mowing speed better than others we have demoed. Now just have to decide on model. The 2500 61" diesel is $10,995 and the 2000 27hp Kawasaki gas 61" is $8600. Leaning towards the 2500 due to longer life and better fuel economy. Figure if we save 1/2 gallon/hour (about$1.50) would take 1600 hours to make up the difference in fuel savings, sooner if fuel costs rise. Would expect the mower to last atleast that long. That would not take into account the increased resale value expected w/ the diesel. Besides the engine both mowers are essentially the same. My CUT is diesel also so would only need 1 type of fuel on hand. Plan on keeping this unit for 15+ years so I dont mind paying a little extra to get a better machine. Thanks.