Thanks to everyone for your responses. The full scale input is especially interesting. One thing missing from our models is the control surface feedback you only get while hanging onto the controls in a full size plane.

Got in a couple more test flights earlier this week. First up was a 1/4" balsa stick taped up the back side of the rudders trailing edge. No real improvement in KE angle of attack control, but it did dampen much of the waggle out . Plane seemed to track better in general. Most noticeable was how well the down side of a stall turn tracked. Also noticed less pitch coupling to the belly while in KE.

Next up was a rearward cg shift of about 1/4". This change along with the trailing edge rudder stick was indeed heading in the right direction. The plane would now maintain KE at about half to 3/4 throttle. Adding power, it would climb. So, it seems that cg is the major factor in how well this plane will high alpha KE. I have a feeling that because of the longer than scale tail moment, the KE cg is shifted farther forward from the canopy area than is normal for an Extra. Seems the long fuselage makes the plane so stable, that it resists any yaw control inputs. Could be the reason the designer used such a silly large rudder area? It looks impressive, but its really just balancing out the long fuselage, and just breaking even.

Kevin