Be sure to check how their underwriters figure out the value of your boat during a claim. I understand that there are several methods used in the marine insurance some good some bad. Also be sure to make sure you are covered if other people drive your boat. I got a quote once where they said I had to fax in a drivers license and social security card of potential drivers before they drove my boat. They reserved the right to deny people after reviewing what I faxed them.
Check the policy very carefully... Most boat insurance does not cover riders very well. Global Marine does - including towing in a tournament. Lots of exclusions for towing riders in most policies. Beware and read the fine print.
I have been with BoatUS for three years. They offered me the best rates and coverage. Have had one claim and the experience was great. Now they have a watersports package that increases medical coverage and gear coverage.