I've got a 60" model. So far, it seems to work fine for me, although there was an issue with water in the top gearbox when I picked it up. I ended up flushing it a few times. I've kicked up a few good sized rocks without breaking anything. The PTO shaft w/slip clutch is a decent quality (eurocardan).
One thing to keep in mind is that there is no direct communication possible with the manufacturer. They absolutely will not talk to an end user about anything. All spares have to come via a dealer. If you have a question the dealer can't or won't answer, you will not get any info from Tarter Gate. I found this out when I tried to get size info regarding a zerk fitting on the side hub. (Trial & error finally revealed it was a 10mm metric fitting)
Nick