Regarding the exact Mp and RPM zero thrust settings.
Does it really matter exactly what they are, so long as the aircraft approximates the performance of having OEI.
Re the mixture V throttle debate
I have only ever had it done that way to me in every assymetric drill in various aircraft, by various instructors/checkies with varied levels of experience. I'm struggling to see why that's a dangerous procedure?
Same here. The big thing for me about using the mixture technique is that all the instrument indications are the same, in that MP and RPM act in exactly the same manner whether it be a simulation or for real. I believe this important for the student to see.
The crux of the matter so far as the NTSB is concerned is this sentence
The Board’s investigation revealed that some flight instructors do use the fuel selector or the mixture control to shut down an engine to test a multiengine applicant. Although this is a recommended procedure, the urgent warning was aimed at flight instructors who were using this procedure at altitudes too low for continued safe flight.
From my perspective it is very questionable that an engine failure no matter how it's initiated should be performed at these altitudes.
By the way using the fuel selector at any altitude to fail an engine isn't very smart.