Round noses work better. In this video Roy explains some of the reasons why. You can experiment with this concept while driving your car. Stick your hand out of the window and keep it flat. your hand will ‘catch’ the wind and you can feel the force of the wind pushing your hand further as it catches, this simulates the wide flat pointy noses of conventional boards. Now ball your fist to simulate a round bullet nose a la these Roy Stuart guns. Your hand feels stronger and less catchy.