Hi Timo and Screamer, thanks a lot for your answers (and sorry Jonster for jumping into your thread!)
Screamer, I weight 84 kilos and I'm mainly using this board for bump and jump in up to 25 knots. I'm looking for a light-wind sail and the bigger one I have is a North Duke 6.4 which I like.
I'm actually dropping the idea of buying a NP Hellcat, probably it's too stiff a sail, too race-oriented with locked-down feel and heavy given its 7.2 square meters. Thinking about NP Expression or NP Excess, both 6.9 square meters. Or, I could easily get a 6.9 Ezzy SE. buon vento!