PRaT, propulsion and speed overlap so much as to render a venn diagram a fuzzy circle. Can't have one without the other two (to some degree) if you want realism. It's part of the completion of the illusion of realism.
Until my present system, I never quite got there. I've said before that it must be partially due to serendipity as it all came together so quickly and so convincingly. People I've had over all had the same reaction: "this is one fast system". One even said it twice in the space of a minute with a shocked look on his face.
It wasn't until my present system that I caught myself swinging my foot or leg for long periods of time and not getting fatigued by it. The body motions and the tempo of the music were as one, varying as the timing changed. I was bemused by it and yet enjoyed it to no end. Maybe it's why I just stopped looking for anything else, and find myself, at times, bemused by some of the responses on these threads.
All the best,
Nonoise