You might want to change the airfoil slightly on the Stickit IV. One of the problems with the IV was a tendency for aileron flutter at higher speeds. I think this was caused by the rearward highpoint of the airfoil. Just put a straight edge on the rib from the rear of the spar to the trailing edge and cut off the curvature, this seemed to help quite a bit. You also might want to look at different motor mount materials. We used 1/2" ply in the kit for economy purposes, but actually flew using the CF/balsa laminates.

Azarr
www.ecubedrc.com