Like Remi told, no races, than go for big sails in 10knts wind to Formula!
If you like to compete I reco you for light winds iS137 with Severne Reflex II 9,7
Than go for iS117Wide with Reflex II 8,6 and 7,8
30knts in choppy water are not any problem with that combo (177W&7,8)!
If you go Sylt,....waves...32knts constant take the iS107 & Reflex II 8,6 and 7,0.
The 8,6 sizes both boards!
Hope it helps!