As stated above, this has nothing to do with vortex ring state.
It has everything to do with the onset of stall on the retreating main rotor blade.
At high forward aircraft speeds (e.g. during max cont check) there is high pitch on the rotors and lift is only being produced by the tip section on the retreating MR blade....due to speed of reverse air flow over that blade.
Reduce the speed of the rotors (i.e. Nr droops) and the reverse flow of air over the retreating blade effectively increases and blade tip starts stalling. At the same time, the other blades are at high pitch with a reduced relative airflow over them. This produces lots of turbulent airflow which causes vibration and the sloppy feel.
Like I said in your max cont thread, this question has set a hyperthetical scenario to get you to think about the condtions and causes.
Ronnie, if you are studying for a foundation degree, maybe you should get a good book on helicopter aerodynamics....where effects such as above are clearly explained.