I would think that the area of the surface being tested has a huge bearing on the amount of torque/current draw required of the servo. A 30% YAK rudder is much larger than that of a comparable sized pattern plane. The holding force of the rudder servo in the YAK would have to work harder to hold that rudder than would a servo holding the pattern plane rudder during a similar maneuver, such as a knife edge. Consider this analogy: a person trying to hold a standard size house door from flinging open in a 40mph wind, compared to the same person trying to hold a barn door in the same wind. The barn door would require much more force to hold than would the smaller door. I guess what I'm saying, is that a better test result can be obtained from testing different aircraft with different flight characteristics.

Jesse