I agree with the majority of what you say. However, what I cannot agree with is Roy Holmes' circular path of finger movement as the norm. It creates far too much destabilisation of the arm- which will end up encouraging stiffness if taken literally at high speeds. For a rapid fire staccato scale, there's just way too much reaction to keep a healthily loose arm. There's simply no way that such extreme reactions can be casually absorbed throughout an entire Chopin Etude, or that the fingers can possibly be slipping enough on every single key for that circular path to accurately describe the product.
First of all, the "circular" path is not Holmes invention, its how the finger basically works.
When your naturally curved finger is on a key -- index finger for example -- and you pull the key down and prepare to again play the same key with the same finger, and do this say at 60 bpm, for a number of seconds, say 20 or 30 repetitions, you will see a natural elipse-like circular movement.
Part of the ellipse owes to the fact that the piano key goes down at an angle causing the finger to slip toward the player. So not only is the finger naturally forming an ellipse, the keyboard action has been designed to assist it.
Its important to do this simple little exercise at a moderately quick speed, so that you can't think about it and conciously inhibit the natural movement that "wants" to occur.
Personally, I don't feel any destabilization with the arm, and my finger is back in position on the key more or less about the time the key pops up under my finger.
But one problem I have with you is you keep changing the topic in mid-stream. Rapid fire stacatto -- are these scales piano or forte? Extremes in Chopin Etudes -- are you talking about stacatto?
Purposely picking something off topic or extreme as a possible exception to a rule, does not invalidate the rule.
Another thing is that Roy's demo is a demo... he exaggerates to get his point across. In actuality, you don't need a lot of pull. The horizontal movement of the finger tip is about 1/2 an inch, and part of that is due to the angle of the finger going down as well as the key going down at an angle. If you over do it, or do it too hard all the time, sure, you'll develop tired overworked muscles.
And no technique will work without a great deal of practice. Endurance, as you know, is the primary type of "strength" pianists need to develop, i.e. the ability to perform many repetitions without fatigue, so one will need to work at this like any thing else.
And when I said the "smallest possible movement", again you're taking it out of context.
Its the smallest possible movement to accomplish the sound you want.
A forte key pull will require more speed/power/energy than a piano key pull or a mezzo piano.
You should listen to Roy's lecture about the keyboard players of old, especially Bach and how he played. Bach was a master technician, and its almost universally accepted that if one can play well the Preludes and Fugues, you'll have a fabulous technique, and anything will be within your reach.
BTW, Bach is excellent for practicing this technique, of fingers on the key, pulling down the key at the correct speed for the sound you want, while the forearm and hand "floats" providing a stable platform and position from which the finger can pull the key down in a natural rotary motion.