Shifty,
I read your post under hardware and have one question that hopefully will help. Did you adjust the deadzone in the control panel for the X52? I don't believe that I have the Pro model, but I do have the X52 (birthday gift also). Is the pro version still twisty stick or rudder pedals? If the deadzone is set too broad in either AH2 or in X52 control panel this might be a problem.
Now, past that, I can only imagine their is some conflict somewhere (grabbing for straws). Possibility that you received 2 bad sticks is still out there. It happened to me when upgrading to DVR for my satellite dish.
Much luck to you in solving rudder problems bud, the X52 has given me some hours of fun and way too many button configurations for my small brain to remember.