When you are TQ limited it also improves the TQ margin - for a given hover power the TQ will decrease as Nr rises. I'm not sure that the L/D ratio does rise - the induced drag will decrease with the reduced pitch setting.
L/D. Cruise at say 75% tq. Beep down Nr to say 97%, tq reduces, inc pitch to get same tq 75%. You now get a higher speed. This led me to the conclusion reduced Nr is good for the L/D. Conversely Inc Nr is detrimental for L/D. I also understand designers design the aerofoil in a manner that dec Nr improves L/D so that in case of a droop in Nr at hover, due to overload or whatever, the pilot still has a chance of a get away.
Secondly, with all these benefits of 103% Nr :- Reserve Nr for droop, inc disc surface, inc TR effectiveness; are there any drawbacks too? Otherwise why have this for Cat A only? This additional safety, why not have it for all operations?
HB