Sasless - it is a fact that phase lag changes as DA increases due to lower aerodynamic damping (thinner air). It is another reason why the precession theory of rotor response is incorrect since a gyro would not be affected in the same way.
My conjecture is that it could affect the amount of flapping due to RBS even though the stall still occurs at the same place - I don't know if it is the case, I am just matching Fidor's experiences to a possible cause.
I have no doubt that Fidor's observations are accurate and that in the conditions he was in the aircraft rolled right - I am just trying to suggest a reason why. Got any better thoughts?