"Ref your bit about the sink. Surely thats down to the loss of flare effect?"
Yes, but lost (i think) because I suddenly encountered a bit of a tailwind and the set up flare was suddenly irrelavant.
Other times when in nil to light wind (especially in a 47) and a flare was initiated a bit early , then laid off a bit and the resultant downwash was then flown down into, when the collective was checked and it dropped like a bomb, I have often wondered whether it was VRS. Certainly felt like it
"Ref your bit about 300' - 20'. Avoid curve springs to mind and the explanation of factors A, B and C equates to where you can and cannot successfully carry out an EOL."
Yes, training, good conditions, spot available and luck, otherwise don't fly in the avoid curve.
I'm not a fan of vertical EOL's and we do tend to merge our terminology in this forum.
For instance I always address an EOL as an Auto. of course the EOL will 1. always have the mandatory, touchdown,
2. not always the usual termination area (say a flare commenced from one foot of altitude for every knot of airspeed) and,
3. only sometimes the developed autorotational flight - at any airspeed.