Anybody have any experience with these? I'm looking at different conversions for motorhomes. Airstream/Westfalia, and Leisure van both make some nice units, but I was curious if they are under powered or not. They have the Mercedes 5 cylinder turbo diesel in them. Suppose to get good mileage, and have a towing capicity of 5,000#. I like the size, but they definitly are pricey. Any Comments?