The purpose of the lower triangle on the 6.0 sail is not really to add extra sail area, but to keep the air on the sail. Wind on the sail takes the path of least resistance, it will spill over the ends if it can. The triangle makes the sail look longer and keeps the wind on the sail. The real world effect is the 6.0 sail has more power down low where it produces less heeling than say a Hobie 20 sail.