I bought from RVDirect back in 2009. Had a good experience - no surprises. I'm about 800 miles away. Picked up the camper and stayed a night at a close by CG to check things out. Went back the next day for a few minor adjustments before heading home.
Since then I have gotten warranty and non-warranty service at several local repair facilities without and problems. Most of the time they don't even ask where you got the camper. Your warranty is good at any authorized service facility.
I think long delays are more a matter of the individual dealership/service department, their backlog, and their competency rather than being on a "preferred" list because you bought the camper from them.
I would definitely buy from them again.