From what I understand....when the control surface is flexed...air streams will find their way between the wing and control surface. At high speeds causing flutter. Also able to get better aerobatic response forcing the air to flow along the entire width of the wing from leading edge to trailing edge without interruption(for lack of better word). This is what Im told by the 2 guys at my field that fly 35% gas Edge's and 30% gas Yaks; who have been flying for over 20 years. They've pretty much taught me how to fly after my initial training sessions. I owe them alot. Thanks Drew and Alan!