I don't fly 3D, but I do fly Aerobatics. I have about the same skill level in both (get the joke, No, I tried!)
I will say that 3D and flying Helicopters will force you to become quick and precise on the sticks quicker than precision aerobatics.
If J3D sets a level of expertise for himself then this is great and much needed in the 3D flying I have seen.

If he is doing rolling harriers in a straight line, not verying the altitude, pitch, or rate of roll while flying this straight line, then he is performing a maneuver that is just as difficult (if not more) than a one roll circle.