TR, I have no doubt whatsoever the techniques you describe work. No doubt at all. You are a better rider than I ever will be so I trust what you say. If you say standing up works, I believe you. Moving your weight back and forward has all of the affects you say it does. But when you start describing why they work I might disagree with you.
As I mentioned before I first looked into this some months ago after reading conflicting opinions online. The consensus from physics types was that the point of attachment (seat or pegs) has no impact on COG. That might seem strange to us lesser mortals as point of attachment has a big impact on handling, but I think we are confusing the affects we feel and know to be real with some fuzzy idea of what center of gravity is.
Once last thing to consider. When I went searching for answers to the physics of how a bike handles I was expecting to find a definitive answer (which I did for the COG argument). But I was floored to learn the physics of how a bicycle steers, corners etc is extremely complex. So much so that physics struggles to explain it. Something a 5 year old can do by touch and feel a Professor of Physics cannot really explain.