Jim, I think modern rotor design has done much to minimise RBS.
After Wessex (which could definitely get RBS) and Gazelle (which sort of protected itself with jackstall but behaved the same way) I went to Lynx with CMRB (the BERP tips) and I became convinced that you could not get RBS with those. The aerobatic flight routines should have been on the edge of RBS given the loading on the disc to produce 3G and do hover to hover back flips but I don't think anyone even came close.
Now helicopters have such high VNE compared to Whirlwind the boundary is probaly much further away in normal useage.