I've seen the VSI against the stop at -4000 fpm in a heavy aircraft at altitude above 8000 ft and we lost about another 1000 ft on the recovery. One of the dangers on the recovery is that unless the collective is handled carefully, the rotor rpm go sky high with such rates of descent. It's all rather academic. People don't get vortex ring with lots of air underneath them; it usually happens when doing something daft, like an approach with an unrealised downwind component. At this sort of height, anything beyond recovery at the earliest incipient stage will not be successful. One of the values of having downwind approaches demonstrated is how differently it has to be flown to keep out of the VRS area.
Re downwind quickstops. You can do a turn and flare at any sensible speed, but for a flare and turn, the entry speed needs to be above about 60 kt or you get very slow around the second half with the prospect of ending up going backwards over the ground in strong winds. It's not a chandelle as the aim is to keep a constant height. The need for a flare and turn only really becomes apparent in helicopters with speed potential well beyond 100 kt that would do a very wide turn or put themselves into retreating blade stall territory by trying to use too much bank to reduce the radius of turn.