The effectiveness of the rudder sort of depends on a number of factors; not the least of which is, how big is the thing. I can't imagine that Bob Hunt's Genesis "rudder" has much of an effect on anything, especially with the speeds we fly. On the other hand, some designs have very large rudders and can have a great effect. There is also the issue of side area aft of the CG. More side area aft mean greater directional stability or less waggle in corners (to a point). Look at the amount of side area aft of the CG on Brett's Infinity. The thing is a barn door. I his case, I don't imagine the rudder contributes substantially to what is already there.