I am looking to buy a new mower and leaning toward a diesel (Ferris IS2500). But a small engine guy told me that he preferred a big gas engine to diesel engine because of torque. He said it was his experience that a gas engine could maintain blade speed better in thicker grass and he attributed that to the amount of torque the engine could produce. I had always understood that a diesel motor produced more torque over a gas engine, but he went on to say that was true only when you got into the higher horse powers (65hp and higher). The other issue with a gas engine I wonder about is ethanol. The higher ethanol blends (E15, E20 etc..) are coming in the not to distant future and conventional gasoline will be harder and harder to find. I have been hearing the service guys (and recently EPA) telling me how hard ethanol blended fuel is on small engines. I don;t want to buy a machine that wont have an easily available and compatible fuel supply in 5 or 6 years. Take costs out of the discussion and what are the advantages or disadvantages of either engine type. Is there a cut difference? Does a diesel "pull" better and keep on cutting on hills or rough terrain better than a gas engine or vice versa. Does anyone know how the engine manufacturers are planning on dealing with the ethanol levels? Will fuel injection engines help resolve the problems ethanol causes in small engines?