Some good points on this thread. Since we are talking about more than just new RV's I have learned some stuff in my experience of buying a much older RV.
If you are very handy and know your way around construction, welding and auto repair an older MH can be a good fit. I have put in a ton of work into my 1983, but I feel my efforts have been very worthwhile. Paying someone for all the work I have done would have cost a good $10K+ on top of what I have actually spent on the coach. So if we are talking $ value of initial purchase price, upgrade parts and labor, that's over $20K in total value.
Around here, $20- $25k can get you a 10 or so year old RV in great shape. I can understand wanting something brand new, with a floor plan you really like. However, if you can find something used with a floor plan you really like, is it really worth a $50K+ premium to buy brand new? If there is a concern with buying used, a PPI from a local dealer is a great option. They know where to look and can help you spot trouble.
Looking at it another way ... I can afford new cars, but have only bought one. The value just isn't there when buying brand new, so I buy used because I am a mechanic and know what I am looking at. Given the problems some other folks have experienced with their brand new RV's, I am pretty happy overall with my chosen option. I have an RV that I am increasingly happy with and I didn't spend $25K (or WAY more if buying at the higher end) to try something out.
I suppose that if you want to finance your RV then loan limitations will lock you into a specific age and price range of RV's. But if you have the cash to buy something up to around $40K, then I see way more value in buying a used RV that has been thoroughly inspected.
Jose