The hydro courses I had taught (and showed) me that the center of lift was 'about' at the 1/3 point. Your original rudder was way off - like a barn door on a cat boat. The modified rudder is closer to the 1/3 model and should be a definite improvement.
My experience with rudder redesign goes back to my old Morgan 24. As I recall, the original rudder was a NACA 0006 or 0008 section - spinnaker up on a reach I'd be up on the weather rail, tiller under my chin, out of control. Changed the rudder to an 18% section - one of the NACA designs with the relatively broad low drag 'bucket'. It was a wonderful improvement - no more stalled rudder incidents, and I never felt that I was dragging around more rudder. Twas a good change.