After over 800 hours teaching in the R22 I have done literally thousands of Quick Stops and trust me, students have messed them them up in every way possible. I can also say that I have never gotten into VRS doing it. Robbies are not that easy to get into VRS, whether you are doing an upwind or downwind quick stop.
However, there have been numerous occasions where there is not much power to stop your decent at the bottom if you get settling a little too quickly, especially if you are heavy which is really easy to do in a R22 with two fully grown adults.
Now I'm not saying that this was the cause of the accident. I just wanted to help clear up the ease of getting into one verses the other.
As far as people practicing the quick stop. Definitely. They are not a dangerous maneuver if you don't do them properly. Only practice can keep you proficient. They are also very helpful in the airport environment when you are doing an air taxi to a helipad or other area for parking.
Ratherboutside