To clear up a misconception, the electrically powered fans still present a load to the engine.
Correct. In fact when hovering the electric fans will impose a higher engine load than a conventional shaft driven tail rotor due to the lower efficiency of electrics.
However as forward speed increases, the electric fan speeds can be reduced or even stopped. Therefore the electric fan load on the engines can drop below that of a conventional shaft driven tail rotor.
Another factor to be considered is the impact of reduction in main rotor speed to reduce noise. Many helicopters today have the capability of reducing rotor speed to reduce noise. This results in reduced lift capacity and engine efficiency. The ability to reduce the tail rotor speed independent of the main rotor speed may allow for additional performance benefits.