I'm sure Shy will remember the dive to Vne (168Kts) in the Gazelle - and then the subsequent pull into jackstall
I certainly do and it always seemed to be unnecessary abuse of a perfectly good helicopter (although it did prove the necessary point to the student).
These days I fly a heli that will easily exceed its 167 kts Vne in level flight, let alone in a descent - slippery little beast. It was quite amusing to once be asked to make "best speed" to fit in between two airliners in the instrument pattern - then to be asked to slow down because I was catching a preceding Boeing 767 on finals.