We've put about 3000 hours on ours.  The problems we have had in that time are a burnt circuit in the range shifter (we repaired), a missing tooth on both front and rear ring gears (never heard of any trouble with that before....but that part number updates to this one with fewer, bigger teeth). several tie rod ends, and a few hoses.  We've put a pair of tires on it and it needs 4 now.  I rebuilt the linkage when we bought it, evidently someone had never heard of grease during the first 1300 hours of it's life, because the parts I built are still working fine after 3000 hours. 

We have a TH330B on the way...big brother to the 220B loran linked the comparison...reading that comparison makes me anxious for the new one to get here!