There is not question that the added 40 to 80 square feet provides more living space since it is provided in the middle of the prime living area. New Coaches with an additional bedroom slide provide more space to get around the bed and perhaps the possibility to place the bed across the width of the coach. If current trends continue, comparable used motorhomes with a slideout or two will fetch a slightly higher percentage of initial purchase price than ones without any slideout. Each slideout adds over 800 lb. In some coaches the slideouts add over 1500 lb.
Many new coaches have less than the necessary carrying capacity even without the slideout.
A further difficulty is that the added weight is towards the front and on the street side. This makes it very difficult to balance the coach and hence handling is impaired. Even the new Ford Chassis at 20,500 lb. GVWR and the Workhorse Chassis at 22,000 lb GVWR will be challenged to carry this extra weight gracefully. I really question multiple slideouts on any Gas or Entry Level Diesel Chassis.