Please don't misunderstand my reasons for advocating the 'constant attitude' autorotation.
I fully agree with Nick and diethelm that airspeed is great, and that the V squared aspect is not well understood.
What I was trying to get across is that if you're going to teach a beginner something that is easy to do and has a good chance of survival, why not start with the constant attitude auto? Once proficient enough at that to survive when the unexpected happens, then start with the variations.
It has the advantage that in nearly all forward flight situations it would involve the helicopter being flared as part of the immediate actions following engine failure, which helps to build / maintain rotor RPM.