I use Severne reflex 6.2, 7.0 and 7.8 on my Futura 93 and 122. This sails work great on the boards. Maybe the boards like powerfull sails like the reflex, but In never tried other sails on these boards. Both freerace as full race sails must work very nice.
Maybe Kevin can add some information about how the boards behave according to more or less power in a sail.