I have never sailed in Barbados but I have been to Cape Town twice and it is one of the most beautiful places I have ever been to. If you are an experienced wave sailor you will be hard pushed to find such a variety of wonderful sailing conditions and if you prefer flat water there is a lake in Table View.
It is definitely one of the places to tick off on your list of places to go as a windsurfer. I thoroughly recommend it!
Have fun wherever you go! Let us know how you get on!