I'm going to have to agree with EG on this one! I built rainedave's SureShark full house, and I'm so glad I did. The rudder is VERY effective and very fun to have - (think knife edge, stall turns, snap rolls, flat spins) I was flying a "A/E 1/2A sport plane" before the SureShark and after flying the 4 channel SureShark, I haven't flown the other one since! Check out my SureShark video in the "Got a SureShark to Build?" thread and tell me a rudder isn't worth it!
All the best,
-Joe