Gee, we can all proselytize endlessly, but I think kcook has a pretty good handle on his own needs It sounds to me that his idea of a diesel tractor in addition to his existing push mowers sounds like a well thought out judicious decision by an erudite individual.
There must be a reason that lawn tractors have seen a precipitous drop in sales as of late. It seems that actual usefullness of a piece of equipment is now being weighed more heavily than how it looks. Lawn tractors were spawned by the desires of people needing a lawn mower, but wanting the looks of a tractor. The majority of people now are becoming more interested in productive capability than looks.
Consumers now are more often buying the tool to fit their needs, an actual mowing machine; i.e. a ZTR, for mowing rather than a miniature version of a tractor that really excels at nothing. The basic lawn tractor is too small and weak to do any heavy work, doesn't have a PTO, doesn't have a 3 pt. hitch, and yet it is poorly designed to meet the needs of mowing because the manufacturers try to look like a tractor so it will sell. The venerable lawn tractor is in that gap where it isn't a tractor, and it isn't designed to be a proficient mowing machine. Sorry, but who is kidding who here? They still will sell, but I believe their sales numbers will continue to drop as consumers buy for their needs, rather than for looks.
So, based on actual needs, kcook seems to be certainly on the right track in my opinion.