I have always believed that an all moving stab should be (mass) balanced.

Recently, after reading the instructions of the Skymaster F15 Turbine model, the instructions call out for no mass balancing.
Instead the use of a very high torque servo is specified ?

Goes against all I know about aerodydamics, but maybe they don't want extra weight at the aft end ?

Your thoughts please.

It sure can't hurt to mass balance the stab. If the stab's center of mass is forward of it's mean aerodynamic center, it probably will not flutter. Helicopter rotors often have weighted leading edges of the blades for this very reason. The higher the airspeed, the more important it is for each part of the plane to be aerodynamically stable on its own as well as having the entire plane being stable.
If the stab's pivot point should also be slightly ahead of the M.A.C. or control snatch can occur.

It might be nice to pivot the surface at the 1/4 cord, as at this point the tail pitching moment sum is equal to zero for any angle of attack.