I bought a mower last year and after looking at most of them, talking to the dealers, reading posts here and on other sites, I bought a 50 inch Skag with a 26hp Kawasaki gas engine. The extra money for the diesel just didn't add up when you figure out how many hours a year it's used. In my case, I'm thinking about 100 hours a year. My water cooled gas engine should get 2,000 hours out of it, or 20 years of use. My guess is the engine will still be working long after I have other failures from normal wear and age. The diesels should get 3,000 hours, so my question was if the extra $3,000 for the diesel engine justified the hope that I'll still be using it thirty years from now compared to 20 years. I'm 43 years old and the idea of keeping any mower going for that long just seemed silly.
I also have the 60 inch deck. I like being able to cut as much as possible, but that deck is a little on the big side for tight areas. It also scalps on uneven terrain. I don't think I'd ever go bigger, but might consider a little smaller if I was doing it all over again.
Talk to both dealers and decide on who you like better. Check to see that they carry parts and that you can get things like belts and blades if you need them.
I started out with a $2,000 budget, then doubled it and ended up doubling it again. I got what I wanted, it's truly a dream mower, but it's funny how much I spent compared to what I was planning on spending.
Good luck,
Eddie