Flight path management is paramount but we start by getting the pilot to invest in the idea that the Nr gauge is his most reliable indication of a complete power loss. From that concept he can build a strategy that works around the Nr gauge.
Perhaps an esoteric debate....but I see the Nr Gauge/Indicator/indication/display....exactly as that....a visual clue as to what the Main Rotor RPM is....and if considered over a period of time...even as short as a mere single second or so....the Pilot can determine what action he. needs to take re Collective position.
I have preached the importance of Main Rotor RPM from my earliest days flying helicopters.....
As Helicopter Pilots we live and die by Rotor RPM or the lack of. Rarely, and I know not of a single case where a Rotor Overspeed killed someone....although I suppose it might have happened sometime in the history of helicopter flight.
In multi-engine helicopters....I place the Rotor Tach at the top of the list for analyzing engine malfunctions.....by suggesting a quick glance at the Rotor Tach shall give an indication of whether it is a High Side or Low Side failure (assuming a steady Collective position) by seeing if the Nr is higher or lower than set prior to the failure.
Torque Needles are the least useful of the gauges for use in deciding what kind of failure you have had.
N1/Ng, then N2/Nf/ then EGT/ITT and if necessary Oil Pressure and Oil Temp in that order.
Are we saying the same thing but in different ways?
Why would we want a high and low RPM horn?
I like the old Huey way...Light for high RPM and Light and Horn for Low RPM....makes for no confusion.