I always found that "weight underside" tended to created a heavy sensation in most people. It seems to emphasize earth over heaven. The sensation developed through exercises like ten-chi-jin is more like becoming denser, so that there is more mass behind ones movements in whatever direction you choose to move that mass, rather than simply down and weighted. I think this is one of the key differences I've found in my own training. Weight underside *generally* seems to slow people down but give them stability. The Aunkai paradigm seems to lead to stability but with the potential for great speed without losing connection/structure.
Not a disagreement Mark, just some conversation.
Thanks for the post. Do you think that when people work on "weight underside", they use primarily a one way conduit. Sort of like everything going to earth which causes them to be "heavy". Or as you said emphasizing earth over heaven. Do you think if they practiced a two way conduit (contradictory forces), they would gain that potential for speed and mobility?