backswing is the only time I am aware of the move by 'feel' of twistaway, I use extensor action to keep from arching too much but if I don't 'do' twistaway to get to manzella flat, I end up at blake flat....
I really notice much better sizzle with the subtle, constant, feel of the twist to maintain 'flat'. I actually tend to feel much more the 'stump' is in directional control, and much more room for the right arm to straighten. Very much the motion in your signature. I just find it harder to adjust trajectory much. Perhaps I need to 'pre-set' the trajectory at fix more intentionally.
I suppose I would consider it a hitter's backswing with a swinger's angled hinge downswing in my case. A 'closed to open' swinger.