The manual for my Ultra Sport 40+ says that the rudder and elevators are counterbalanced to prevent flutter. Wide open passes are freaking fast, and this is my first ever kit build, so my hinge gaps could pobably be better, and there's no sign of flutter!

How does counterbalancing help flutter? I can see how it would reduce servo load because the part of the moving surface ahead of the hinge line is actually generating forces complimentary to the servo movement, but I don't understand the flutter thing.