I just sold my 2005 PW with a Ford v10 engine on a one ton chassis. From day one I was repeatedly turned away for service at numerous Ford dealers because it was too heavy and their lifts couldn't handle it. This was a classB! In my town with numerous Ford dealers, only one will handle it and you have to have an appointment weeks ahead of time. One dealer said they would not handle motorhomes because they're big and take up too much of the parking lot. I think it's a fallacy that having more brand specific dealers is always the answer.
The last time I spent $2,000+ at a Ford dealer to have the differential serviced they used after market parts but charged me for Ford OEM.
I now have a new rv on a Sprinter chassis and am not expecting things to get better service wise when compared to owning a Ford. I'm just saying things aren't what they always appear. I going to buy the Mercedes factory manuals, bring a lot of tools and hope for the best.