The Sprinter will be a 24 ft or so MH and depending on how you drive and if you tow, will get you 15 to 17 mpg (Diesel of course) One nice thing about the Sprinter is the TIGHT turning radius, easy to maneuver into a parking space in a fast food parking lot (or museum or wherever). You sit up high and it has good visibility also.
You can easily get into the Mercedes vs everything else cost to operate, yada, yada arguments, but I am simply trying to point out a couple of advantages of the Sprinter chassis, since you are desiring a MH in this size range.
Charles