A few years back I bought Lund/Mercury package at the Toronto Boat Show. I had gone to the show earlier in the week, but returned on the last day and was able to negotiate a really good deal on a floor model. One of my concerns was, if it ever needed warranty work, that the dealer I was purchasing it from was in SW Ontario, but most of the time I would be keeping it at my place in eastern Ontario. Before pulling the trigger, I walked over to the Mercury display at the show and spoke with one of the factory reps. He assured me that any authorized Mercury dealer in Canada is obligated to perform warranty work for any motor purchased in Canada.
Fortunately, I've never had an issue with the motor. I'm not sure of other mfgr's, but generally the purpose of a dealer network is to provide widespread standardized service for a product.