I'd recommend someone like Warren Trafton
http://www.yachtworld.com/syri/ even though he works out of RI - he is extremely knowledgeable and very pleasant to deal with. I plan to have him list my boat...
To me the value of "working" with a broker as a buyer is he can bring to the process years of vessel and yachting experience that simplifies the tire-kicking process for you the buyer. He can save you a lot of time and travel, both based on his knowledge of whats worth looking at, and his ability to extract information from the listing broker that you might not get. By working with a broker I mean turning the whole search process over to him - tell him your needs, expectations and budget and then let him lead.
Looking at boats can be fun - if one wants the full tire-kicking experience, such as taking a weekend to fly from Boston to Annapolis to see an ideal boat, but finding it not worth stepping aboard, then go it alone. I personnally think you end up paying the same for a broker boat whether there's a second broker involved or not, if that's true, your use of "your" broker is free...