HAHAHA, sorry man but this is now the one guy that you cant even ask that question. Bruno doesn't have a hull with fins. he has a hand full of boards with a boatload of fins and changes combination of boards and fins up accoring to the days conditions and location.
I guess the only answer to this could be he is on Paolo boards and fins.
that is what i would expect. There was a time when windsurfers carrier more than 10 boards and 20 fins to a race event.
The question is what is the design he is using that works so well. Of course he is not going to be the one to tell.