Wing sail has been used on Moths and the A, my understanding is there are equal to or less lines than conventional sails if rigged correctly.
Issue is cost, durability, transportability, and rig-ability. They are really neat but the engineering and materials have a ways to come before its a mass market product IMO.
As the boats get smaller, there is also a technical trade-off with the extra weight aloft with the wing and pitching moment of the hulls. Ben surmised that the A-cat is pretty close to the threshold where a rigid wing (and the weight built with current technology) added enough to the pitching moment that it slowed the boat about as much as it sped it up. Granted, wave conditions play a big role here.
