It won't affect motor driven helis as much becuase the tail speed is controlled seperately by an independant motor. On a driven tail helicopter, the tail can only go as fast as the main driving motor allows it to. Hence, during spool up, if the tail isn't spinning quick enough, no ammount of pitch will counter the main torque being placed on the helicopter by the main blades untill the overall headspeed (and tail speed) picks up enough to generate the required thrust.