aa777888 - is that the same FAA handbook that called settling with power and VRS the same thing?
So you will throw the baby out with the bathwater, then? I bet you can't name one book that doesn't have either a single error or something you don't agree with. So that's a ridiculous way to imply the entire document is worthless. And they've since updated the handbook to only discuss VRS. So perhaps not entirely correct but getting better.
Go and try a transition to forward flight on a still wind day from a 15' hover - don't change the power but move the cyclic very slightly forward. You will start to descend as you have tilted the lift vector, then as the speed starts to increase you get inflow roll (transverse flow) which makes the aircraft roll towards the advancing side - correct that with lateral cyclic and you will next feel the vibration of ETL as the rotor passes through the roll-up vortices of the downwash - then the nose pitches up and the aircraft climbs as the rotor experiences cleaner air.
Transvers flow is a flapping to equality in roll that exists throughout the speed range but is most noticeable just after the disc is tilted forwards to initiate a transition. Not associated with vibration.
"you will next feel the vibration of ETL as the rotor passes through the roll-up vortices of the downwash"--that's not ETL. If it was fully developed ETL and there was a vibration associated with ETL the damn helicopter would vibrate all day long like that, and of course it doesn't. And if it's not fully developed ETL then it's not an optimally safe condition to be making the approach in.
Every reference I've read to date says the vibration is due to transverse flow and not ETL. Therefore they are ALL wrong and you are right, or you are wrong and all of them are correct.
Of course I am by no means an aerodynamicist, therefore I must rely on what these references tell me is so. Can you provide a written reference (other than your own!) that does not say that these vibrations are due to transverse flow prior to accelerating into ETL, or the same but after decelerating out of ETL?