You left out the vibration due to tail rotor bearing failures which has caused a number of incidents a while back.
Did not know an AVC would be needed just coming off a pad. It thought they were normally for high speed.
I did not say there have not been nor could not be a serious incident, hence the crew returned, but I am stating that the most likely thankfully is not serious, and bearing failures and other serious failures have been extremely rare.
And as Paddy says, the AVC is on all the time, and is used all the time. Fly without it and kiss goodbye to a good-nights sleep for a few nights as your tinnitus will be roaring like a good 'un!