For single rotor helos, , lift loss is increasing with speed, it's compensated with blade pitch adjustments on the opposite sides, which causing more and more lift loss obviously. At one point it cannot be compensated more as the speed difference is huge, that is when it stalls and start to roll the plane.
This is causing the speed limit of helos and its hard to get around that.
For coaxial rotors, lift loss and retreating blade stall still occurs although due to air movement its not that bad is it is with singles. It starts with lift loss and vibration, no clear roll effect to either side. Later on you'll have increasing vibration and finally loosing blades, they either break apart from huge forces pushing them or hitting each other (which is really a bad thing with coaxials).
Sorry if something is not clear, I am not a native speaker, especially writer, not to mention, that I am not a helicopter expert, just interested in the topic....:D

Edit: Just saw what you copied. Yes, its sounds correct, but I think we need to do a couple of things, before we can argue on the exact speed limit and simulation of forces for coaxial helicopter blades