I just revisited this thread, and one more thing to consider is to buy your sails from someone who has multihull specialty designers on staff. Make sure those are the people who design your order. I've been told by my boat's maker that multihull sails need to be cut differently due to higher anticipated apparent winds, and that the fabrics have to be reinforced more and at least twice as heavy for a given size and wind speed, because multis don't heel significantly (and don't spill the wind as much in gusts).