The way I looked at it was that, for the warranty period, Kubota "owns" my tractor, so I figured if they want me to change it, I'll change it when they want. Like Messick, said, I may cheat it later ... after the warranty expires. Maybe push it to 4-500 hrs or once a year.
Just wondering about your brother ... does he have a hydrostat drive or gear?
Cheers!