If a dealer is so busy servicing their own customers they might be reluctant. Also, they are more familiar with the brands they sell. The equipment like generators, refrigerators, stoves, microwaves, water heaters, air conditioners, etc. are all pretty common and should be serviceable by any reputable dealer. Then there are many RV service centers that are non-denominational (no RV brand sales).
Warranty work is usually the biggest hangup. I had warranty work on my Great West Van in Florida and all it took was a simple phone call to Winnipeg and the assurance GWVan would pay the bill. Great West Van only had about 3-4 dealers nationwide at the time. Advanced RV has no dealer network but they assured me they would handle any warranty problems in a similar manner. I would like to know if the manufacturers that have extensive dealer networks whether they would be more reluctant to allow an independent do warranty work. No manufacturer has that extensive or convenient network unless there is one down the road from you.
Discount off MSRP is an age old game. MidwestRVSales.com runs a weekly ad in the Minneapolis Star Tribune newspaper. They list MSRP price alongside Special Pricing. Dealers do the same at RV shows. Am I to assume the special price is the final price? It didn't work that way when I bought my first B in 2006. The dealer had posted an MSRP and a sale price. I still counter offered my price and eventually brokered something in between my price and their sale price. At the same time shortly before striking that deal I walked away from another B when I could not get my price or close to it. It really all comes down to how much the dealer wants to move inventory.