One of the local guys here built a F-16 a years ago and inststed it have all internal linkages. which I warned him against. Every time we flew it it had rudder and or aileron flutter at high speed until we moved the linkage to a std R/C style exposed setup. He didn't belive me when I calculated the required torque at over 300 in/oz to move the rudder 10 degrees and hold it there at 180mph which was easliy posible with the engine he had. installed. Rudder is the easiest surface to get flutter on since it has no aero load if the plane is straight. BV had an addendum to the Bandits years ago where you put a 90degree strip from plastruct at the trailing edge of the rudder to aero load the rudder to one side and it stoped the buzzing. Bottom line is what Bob said "a servo arm and horn is a proven, robust, inexpensive, and light way to transfer the torque from servo to surface... "