Phantom 1

ETRM helicopters use more power to turn left than right, with clockwise rotating blades. That is because the motor slows or shuts down and only the torque from the helicopter's body turns it. Again, it must be a clockwise rotating main blades to make it harder to turn left. If it was CCW, it would be harder to turn right. They are all the same. There is only so much torque available when the motor is off. Those tail rotor motors don't reverse, just slow down and turn off. Belt driven tail rotors are more precise, but still need more wind one way than the other. Battery level is negligibly increased, as you fly in forward flight and the motor does not to run so fast, as the tail weather vanes behind the heli, but not enough to matter in the grand scheme of things.