I have a 2016
M62 with a little over 600 hours on it. I've busted a couple of hydraulic lines on it, but other than one issue, it's been a very reliable machine. The local hydraulic shop made up replacement lines while I waited and I was back in business the same day in most cases.
I had a problem with the valves on the Kubota top'n'tilt kit leaking down, letting attachments on the three point hitch go rapidly out of adjustment. I went through two kits before I requested and got a refund. They were replaced with valves from Brian at FitRite Hydraulics. If I had it to do again, I'd just order the lines and fittings from FitRite to start with.
The regeneration system has been no problem at all. If the cycle starts while I'm using the tractor, I just keep on working. The sound of the engine changes a little, but otherwise I can't even tell. Once in a while it'll start regenerating just as I'm putting the tractor away, so I'll bump the hand throttle up to two or three thousand RPM and let it sit until the cycle is over, maybe ten or fifteen minutes. It started once when the tractor was out in the middle of a field of dry grass, so I moved it onto bare dirt out of sense of abundant caution. Don't wanna be that guy in the middle of wildfire season.
Just out of curiosity, what, if any accessories are installed on the tractor you're looking at, and how much are they asking for it?
Kubota has a build page that lets you custom configure a tractor, and you could use that to get an idea of what the subject tractor would cost if you were to buy one today. You might also call a Kubota dealer and find out how long it would take for delivery once you placed an order.
You should also take into account how much it will cost to ship the tractor to you.
Also find out if the seller has maintenance records and receipts for things like hydraulic oil and filters.
As with any at a distance transaction, be very careful about how you go about assessing the condition of the tractor, as you are buying it site unseen. If you're buying from a dealer or auction house, see if you can find online reviews for them, and check with the BBB to see if there are any complaints against them. If there's a Kubota dealer nearby, you might consider paying them to do an on site inspection of the tractor. And when it comes time to pay, use an escrow service so you have recourse in case the tractor was not truthfully represented.