I used one this november when moving my boat from Virginia to Puerto Rico.
loved it. The only time I had coverage problems were in severe storms, where only 1 out of 2 or 3 msgs got out. once it cleared up, all went out fine.
It really kept friends and family back home in touch with my progress, which really kept the concern down in their minds. I also bought the Search and Rescue package for the 911 button. Glad I didn't need it.
I set my messages up with my "Standard" message that all was well - my help message was that we were having problems but ok (just in case the next one was 911 and the Coasties contacted my primary contacts - they could inform them of the amount of time we were broadcasting issues prior to calling for them, just in case.
In talking with the Coast Guard in PR
, they also told me they recommended the system to boaters as it really increased the ability to track and connect when needed. This, coupled with a Sat phone for downloading weather maps and making calls when necessary completed our ability to effectively communicate. Also had a 406 epirb on board.