I have done almost all of the repairs to my boats over the years, however once in while I needed the dealers assistance for repairs or parts. This is my experience from the past twelve years:
Mack's Dock/South Harbor Marine, Waretown- dropped boat off in early spring (slow season) for engine idling problem I could not figure out, after a month or so they found the problem that was a pretty simple fuel delivery problem fix that I was not aware of. While they were at it they also replaced the stator (that was a few months old) and the flywheel magnets (that were also new) . When I inquired, they just wanted to discuss the roughly eight dollar check valve that failed (I did not know it existed) and handed me a invoice for around $800. This was twelve years ago, since then I have had many people tell me they are very good at what they do. I suppose I just got a not so good mechanic. Bought a few parts there over the years, they were pretty easy to deal with.
Pelican/Ocean Beach Marine, Lanoka Harbor (Cedar Creek) - Did a start up for me ten years ago and offered many tips over the years. Bought most of my parts there and was able to pick a mechanic's brain on a few occasions. Last year had a gauge problem on my 06 Marlin and it took a few attempts to replicate and repair the problem. They were more than willing to help me out, just were not real familiar with the latest Yamaha command link system at the time. In thier defense, the command link system was only around for two years or so at the time, and message boards on the internet also were little help. They did finally fix it and the gauges have been fine ever since. The staff was always friendly and helpful.
Sun Harbor, Barnegat - Owner is stand up guy, staff is friendly and willing to help. I have not met the mechanics but I have been told they are excellent. Prices for parts are pretty good, especially for a local marina.
Hope this helps.