Kwe : You asked "what to expect?" In my article I found that there was NO more uncontrolled "rounding up into the wind" while beating. However, with the added surface on only the trailing edge of the rudder, expect it to be a bite "heavier". As I point out in my article Catalina compensated for this in the MKII by installing a larger wheel for more mechanical advantage!!!
But, you'll enjoy the better rudder control especially with your wing keel. Don't believe that the elliptical change is so noticeable if you have a C34 fin keel rudder.
A few thoughts