9Aplus - O.K., maybe I was being a little over-optimistic as regards the design improvement potential of the Diamond engineers electric-powered fenestron tail rotor.
However, Prof. J. Gordon Leishman at the University of Maryland tells us in his helicopter aerodynamics writings, that the typical open tail rotor of your average helicopter consumes around "5% to 10% of the engine power".
It's not unreasonable to presume that an electrically-driven shrouded tail rotor of a perfected new design, would be able to halve that power requirement. Therefore 2.5% to 5% of engine power required for the tail rotor could be possible.