I have been watching the wing rock discussion. I built my SU stock with the rear elevator location. It came in right at 16.5 lbs or a bit less with the CG right at the center of the tube. I have been very pleased and impressed with the performance. However, wing rock in a right side up harrier is quite pronounced with no aileron input at all. I have never been able to stop it with aileron input (I can make it worse though). The good news is that it never snaps out of it ... it just gets quite exciting if I get lower than I should be. Inverted it is rock solid with no wing rock at all.