Thanks everyone for the really useful information, and also thanks for the private messages I have received.
I will be doing some experimenting over the next few weeks with a rigidly fixed camera on the nose. That should show just how much of an effect there is from the vibration.
I’m also going to arrange to do some tests using the Robinson R44 with the company owned gyro mount. When I have seen it on the news I quite often detect a vibration, but that might be at the end of the telephoto range, whereas I’m only looking for wide angle, direct ahead point of view material.
Thanks again.