crab said, "Matthew, I think you are saying that you agree that flapping/coning is likely to be the initial reaction to a lowering of the lever. I think that is the answer to the original thread question and all the stabiliser stuff is a secondary effect once the RoD has been established."
I probably did, but that's not exactly what I meant to say. I think most that are in favour of the flapping/coning argument are correct if you limit the reaction to a very short time period. If you're a designer or a tester, limiting it this much is needed, but if you're just trying to understand the helicopter I think you should go beyond the instantaneous reaction and look at a larger picture.
The larger picture is that when you lower collective, you reduce the blade pitch, create a rate of descent, and throw the helicopter out of equilibrium. From those you get reduced coning which changes the disc angle, changes in lifting and dragging surfaces due to the rate of descent, and moments about the center of gravity due to being out of equilibrium.
By answering the question with all the above effects (and even more that could be added) you make it very difficult for a designer to do anything about it, but you help the helicopter pilot understand what is happening to his machine.
Matthew.