Point where TR-VRS occurs
Nick,
All depends on the loading of the heli and the size of the fin.
As you know I did all calculating experimenting with a R44 I and II.
Very light it requires little tail rotor, so the danger zone is in the low end.
Heavier it will require more tail rotor so the induced speed zone goes up in the ranges you indicate. (I did not check the precise speed here and now, and wish not to make a point of discord of that, if I have time I could dig into the archives, but that is not the point I am trying to make)
It now can look synical but a small tail rotor will have TR-VRS in a higher speed zone because its induced velocity will be higher (higher disk loading), so the under-powered B-206 will encounter it at higher left wind speeds....
There is by the way a big difference in my personal experience between R44-I and II MR-VRS risks. A light R44-II with the bigger MR is much more prone to MR-VRS because of the low disk loading. I would say 100% (my statistic, never had one in the R44-I but I had many in R44-II, so I always keep positive vario in that case)
d3