Yes F-16's are nortorious for rudder flutter. I had a Spiderjets one and I massed balanced the rudder. The servo was not nearly so powerful as yours but I had no flutter problems thanks to the balancing.
What I really loved about the model was the ridiculously slow and precise landings. I think you have chosen a good colour scheme too, as I discovered that low vis camoflage really works!
Regards,

John.