Op you are asking all the right questions and there are a lot of trade offs in comparing a 30 ft gas MH to a 40-45 ft DP. I fixed the noise and heat problems on mine with $20 worth of insulation but it will never be as quite as a DP with an engine 40 ft behind you. I can still talk to my wife talk when hill climbing. A 40 ft DP will probably weight 30k lbs or more and maybe have 360 to 450 HP. A 30 ft gas will weight half as much with 340 or 362 HP (WH or Ford). It is HP to wt that will determine performance. I would choose a 30 ft MH with 362 HP over a 40 ft DP if performance was my only concern. The ride on a DP will be smoother but you will still feel pot holes and rail road tracks, the exhaust brakes on a DP is a plus and saves your chassis brakes, and feels safer on very steep long down hills, but having said that I just had the brakes on mine changed after 104k miles. I bought this used gas MH to learn about the lifestyle and figured after 3 years of travel I would know what I wanted in the next MH. After 11 years of ownership I still have not bought a newer one the only thing I know for sure is that I want to stay within the 30-33 ft range. Good luck in your search and remember everyone will have preferences and opinions that may not fit your situation.