Have you noticed that EvoX ,Speedster and RS-flight have head extends above top of mast, so looks more like "pointed" sail?
This feature is well know in aerodynamics,reduce wingtip vortices,reduce overall drag and make sail/wing more efficient.
Long time ago there was NP Z1 with this aerodynamic trick:
www.windsurfing44.com/matos/Neil_Pryde/1999/Neil_Pryde_1999_Z1_en.pdfevoX
ezzy cheetah
pointed wing
