I did buy a higher end 5er used and have been very happy with it. Being able to do my own repairs has allowed me to not need a warranty. My only concern is that I feel high end 5ers were most likely purchased by full timers as a means to justify the cost. Personally, I wouldn't buy a used full time rig as wear and tear will be multiplied. If necessary, I would step down a notch in quality to get a lightly used unit.
The older high end units are heavy. Some of the money saved might have to go to upgrading his truck. Something to consider.
