212Man,
You are correct of course, and I guess I didn't say it very well. As I read Thud's question about Nr, I now realize he was refering to drooping during a topping check, not operationally. Allow me to clarify...... My point about RRPM being most efficient at 100% is for AEO, normal operations. Steady state, the 212's asymmetrical rotor works best at 100%, and drooping it (to lift a heavy load for example) accomplishes nothing once the stored potential energy is depleted.
For topping, I agree that sticking with 97% may not always be practical, and one really wants to see evidence of a positive Nr decay. If that requires drooping below 97 then so be it, but refer to the caution at the end of this post.
Similarly, things are a little different in an OEI landing event. In this case we are not concerned with the flight manual steady state, power-on limit of 97%, and we droop the rotor to whatever is necessary to soften the blow. In doing this we simply consume potential energy stored in the rotor, as one would at the business end of an autorotation.
A word of caution about low RRPM at high power: Here you're in No-Man's-Land with respect to yoke, pitch link, or blade loads. The RFM limitation of 97% power on is intended to prevent prolonged operation in this area. Ideally, one should carry as much RRPM on the approach as possible, and delay drooping the rotor until you need it.
I hope this clears the mud a little. Have a good holiday.