While I don't have any direct information to offer I wanted to make sure that you saw this thread -
click here
The impression I get is the OEMs try to make the process of applying for warranty payment at retail rates seem more difficult than it really is.
It would be interesting to know what percentage of dealers who operate in states with laws requiring retail rates for warranty reimbursement actually receive the higher payments? I'm betting that a fair percentage of dealers don't want to raise the issue with their OEM and see it as another form of "franchise insurance."