The Caribbean 1500
used Commander's Weather for both weather and Gulf Stream
analysis each of the two times I did that trip on my own boat (2004 & 2005). The key features were predicting a weather window for departure from Hampton, VA, which allowed us to get across the Gulf Stream
in settled conditions, daily update forecasts of developing weather features and windspeeds and direction, and the locations of the main stem of the Gulf Stream and the cold eddies to the south of it. They did a credible job.
I also used them to provide me with an initial individual weather forecast
with subsequent daily updates by email
(Sailmail via SSB) for a passage
from the Abacos, around Cape Hatteras, and into the Chesapeake Bay
in May, 2006. Again, I was very satisfied. My experience was that they tend to be a bit conservative, in that conditions didn't turn out to be quite as bad as forecasted--probably a good thing.