It seems as though whether a squaretop would be an advantage or not would depend on a combination of crew weight and the conditions you mostly sail in.

My understanding of the squaretop is that it gives you a little more sail area and power in light air but depowers the boat in heavy air, because the top of the sail blows off (sort of like a Chinese junk). So if you are a heavy guy who sails in heavy air most of the time, I wouldn't think you would want a squaretop -- you would want to be able to take advantage of all the power you can get get. If you are a heavy guy who sails in light air most of the time, maybe the squaretop would be helpful. A lightweight guy, on the other hand, might really benefit from a squaretop in heavy air because of the way it depowers the sail.

Am I wrong?