Diesel, what was your experience?
My experience with a couple of 30 year old Yanmars is they were built for owner maintenance and nothing has broken in the time I've owned them (11 years, 5 years, 1 year) - at least if you don't count dumb owner mistakes such as ripping out the oil pressure sender wire rassling a fallen tree. No need to go to a dealer (none exist for these old Yanmar-USA models). Mail order parts are available from Texas for normal owner maintenance.
If you earn your living with the tractor you need a full-service dealer nearby to get you back on your feet in case of problems. For a weekender where waiting for mailorder parts is no big deal, I would save the $thousands that is the premium for a local dealer offering same-day repairs, and buy the Yanmar if it 'just feels right' for you.
Yanmar's assurance of an approved mobile tech for warranty work is all the guarantee I would need if it does turn out to need some dealer setup to conform to spec. After that, I think Yanmar got it right and I expect it would run for years with normal owner maintenance.