Do you have the large elevator for the KF4? Worth getting if you don't. My KF3 had the short elevator and I needed to retract the flapperons to get a good bounce-free 3-point.

FWIW, someone at Kitfox (don't remember who) told me the elevator was more effective at low speed with gap seals and the airfoiled ribs. Sorry, for sure I don't have any numbers.

Also, the ribs for the stab and elevator are pretty cheap as Kitfox parts go.