I guess the reason for my "bigger is better" thinking is my lifetime of running heavy equipment. Nothing makes for a long day like having a D4 where you should have a D6. Carrying a wheelbarrow full of dirt is, .....well, for a wheelbarrow ! And spinning your wheels pulling a 6' disc is burning up fuel and time that I could better spend in another endeavor. My 57 hp Kubota served me well, but I intend to get an 8' mower and possibly a tiller, so I moved up one size. I bought it after plotting and mowing season so there won't be any proof until I've used it doing what I've done with the other one.