
You will find that many if not most of the key issues you raised are dealt with in 'Beginner to Bubka" - and you will find little or no disagreement there/ However i believe it really is time to begin to use the 'right' words to describe what is important, even if we have to create those words.
There is a Chinese saying "The beginning of wisdom is when thing are given their proper names". This is why I made the distinction between a Free take off and a 'Prejump' -a term I came up with after meeting Petrov and he described his - at the time revolutionary - concept of the take off.
To cut a long story short and only to try to clarify what i see as a difference i have suggested that a free take off is a failed pre jump! As Bubka stated in jamaica he always TRIED
to 'prejump' -ie be in the air miniseconds before the pole tip hit the back of the box and "He achieved it a few times".This means of course that the rest of the time -but, as you correctly implied, probably not all the time - he had a free take off where although his 'toenail' was still touching the ground the pole was still straight -ie not loaded until after he left the ground.
I believe the terms 'free take off' and 'prejump' can be used to more precisely define actions - and are therefore more likely to generate wisdom - than 'transfer of momentum' - which can generate many different pictures of meaning. Note that i have also invented and used the word 'upspringing' to convey the essence of the take off. After watching hundreds of US vaulters at the summit on four trips I felt something had to be done to combat the prevailing-- ' take off under and simply let the pole rip you off philosophy' I saw; hence the new word which ties in with StabHochsprung -saut al la perche - salto con lasta etc.

Thought for the week 'Wisdom can come from any place ,any time and in any language'