We purchased a 2001 GB Cruisemaster 37 1/2' DP with 44k miles about 6 months ago. Very clean coach that had always been in covered storage. Major factors in purchase were floor plan, large pass thru basement storage, freightmaster chassis, 300 Cat engine, etc. So far very few problems. Areas of concern were age of roof, tires (08 date code Michelins) and lack of maintenance records. We did get all the owners manuals including generator, appliances and such. Any maintenance issues have been minor things that I could fix myself. If your not into that type of maintenance an older coach could be more prblematic for you.
On the plus side the coach runs and drives like a dream. Since this was our first DP I can't compare it to any other coaches but I wouldn't hesitate to buy another one based on my experience so far with tis one.
One Caveat. I did have to get a Non-CDL class B license to be legal to drive the thing in Texas (over 26,001 lbs GVWR). That includes a written test (including air brakes) and driving test in the RV. I'm not sure where you live but I would check on that before you purchase and let that be a factor in your decision.
Good Luck, whatever you decide.
2001 Cruisemaster/300 Cat