PTO brake has been an issue in the past, as said if all it's done is plow, it won't be an issue for you for a long time. If you use the pto, slow the engine speed to idle before disengaging. Same for engagement. Idle. Sorta expensive to have to replace the brake/clutch assembly--as the original is no longer available, so you have to upgrade to the M-60 series pto brake clutch assembly, about $2000 as I remember + labor to split the tractor for access. I think I did about 6 or 7 of them, the hard way since the boss didn't want to buy tools to split tractors (had to use a fork lift, pieces of firewood, concrete blocks, and a floor jack and scrap iron)
Had a few "clutch" return spring falling off. No big deal just makes the engagement of the clutch pedal kinda jerky.
Only other issue was air conditioning....guys letting their pets ride with them and the a/c sucks the hair into the evaporator. No big deal, remove seat and the plate under the seat, remove the top of the heater box and pull the evap out for cleaning (cab models only obviously). Not hard to do.
pretty good tractors in my opinion. I'd pay good money for one over a DEF equipped tractor at least until Kubota gets the DEF stuff fixed.