I sailed a classic Tornado (pinhead sail). Now I sail the new Tornado (square top). I doubt the new one is faster when reaching in heavy wind (both double trapeze). At the classic T. center of effort is lower and probably less drag. In heavy wind you try to eliminate the top of the square sail by a lot of downhaul so this makes it more or less a pinhead sail. However this is in contradiction to speedwindsurfing where you see a square sail with a loose leech. I think the topspeed of a catamaran (no spi) is for 99 pecent fixed by maximum heeling moment so in the end it makes no difference for top speed what kind of sail is used as long as the trim is correct (flat!).