Stick with your 26 EFI. The extra weight and price would outweigh the benefits in your case. The extra torque would be nice for your 74" deck but overkill for your 42" deck and troublesome in the cold weather for your snow blower. With a Diesel you will also have to worry about not damaging the cooling system. With all that said the diesel is a nice option if you plan on putting more than 4000 hours on a machine. Last year we purchased a MBSY with a diesel and kind of wish we kept with the EFI option mainly because of the weight and size issues. We have had great success with all of our EFIs and usually get 2000+ hours out of them without any major issues. Your machine has low hours on it, stick with it!