You mean other than the current US Nats, World, and European champions? I've used it. I think it allows you to get more optimal flap-elevator ratios for round and square maneuvers than having the same ratio for both. It also reduces hinge moment for large control deflections, allowing you to fly more accurate corners. I'm not sure I am getting the max benefit from it, because I don't know how much the controls on my airplane move. I have it installed in an Impact, which may have different flap deflections in maneuvers than a Max Bee.