Hmm, I don't have any personal experience with them, but I didn't know they did conversion work. ... I guess what I'm saying is from the engine perspective, how is a conversion any different from any other bus?
Craig, to be clear, I did not suggest they did conversion work.
I, too, tend to look at a converted bus as fundamentally no different than other buses, but I can tell you from experience that many shops take a different view.
We have been charged the "motor home" rate rather than the "bus" rate at several engine shops, some of which are actual Detroit distributors (and would someone please explain why there is a higher hourly rate for buses and motor homes in the first place? If it takes longer, they bill for more hours anyway). And once when we pulled in to a commercial tire shop, which was happy to work on buses, they refused to serve us because we were clearly a motor home. (We eventually persuaded them to do it.):http://ourodyssey.blogspot.com/2007/10/day-of-frustration.html
There is actually a reasonable basis for the refusals: motor home interiors are much less tolerant of mechanics and their outerwear than either trucks or buses, and many service items require access through the interior. Some shops are afraid of large cleaning bills (don't laugh, it happens). Additionally, conversions often have made access to certain things more difficult, by placement of furniture, cabinetry, etc..
More than once, we've had technicians remove their footwear, walk through the coach, then put it back on as they climb down a hatch over the transmission, only to have to repeat the process several times during the procedure:http://ourodyssey.blogspot.com/2008/01/our-moose-is-gone.html
Things are generally easier to get to in a seated coach, and the flooring and even the upholstery is more tolerant of the occasional greasy footprint or dirty hand.
I can't really speak to what the underlying reasons were at SOD, I just know for a fact that we and others have been turned away there.