What does engine power have to do with instrument flying techniques and procedures? Does the donkey know what kind of visibility is outside? It is the Jackass in the pilot's seat that has to consider that part of things.
A whole generation nay...at least two if not three generations of US Army pilots trained on Bell 47 helicopters rigged for instrument training. If one can do a 412 ATP ride in the Sim...why not the instrument rating as well?
We have got to get away from doing it the way Wellington did it folks!