I was on the Wind Dancer when in was based at Grand Turk. I'm thinking of doing the Grenada trip, but no one will have reviews of it yet as this is the first year they are doing it. They used to have the Island Dancer based there which sounded great until I read complaints that they didn't really head far from Grenada to hit things further north in the Grenadines as originally planned or implied, which to me would have been the point of doing the trip. (I heard this was due to customs/immigration, but the cynical side of me suspects fuel costs.) I'm hoping this will be different, the Wind Dancer carries more passengers so maybe it will be more worth their while.
The Wind Dancer itself is an ok boat, older and not quite as slick as some other Peter Hughes boats but fine. Roomy public spaces but some of the cabins are pretty small. The lower the number the bigger the cabin. We booked late and were in one of the smallest cabins, couldn't have 2 people doing something at the same time at all. They get a little bigger as you go forward and the bit of extra space looked like it would make things much more manageable. The Master cabin #1 was palatial in comparison, on the upper deck away from all the others and only accessible from outside.