Chopjock,
If I was in the cruise, 125Kts in my 500 and the donk quit, I would most certainly not lower the collective until slowed to at least 80 Kts. I would be pulling in aft cyclic first.
And if was flying at 155 kts in my twin, I would lower the lever slightly and carry on straight and level. It will fly at 125 kts on one engine.
Problem here is that some are trying to find "one size fits all" advice. The correct actions for one aircraft may differ from another. The actions in one set of circumstances need to be quite different for the same aircraft in different circumstances.