We have sailed twice in Cat H cabins; 664 both times. Did they vibrate; yes. Was it a nuisance; no. I don't think it is too big a deal.
Our next trip is in a Cat H guarantee. We are actually hoping for one of the Cat C stern cabins to get the large balcony. If we do, I will report back. My mother, who had a harder time living with the vibration, has taken one of those wonderful Cat G midship cabins. To each their own.
