I always thought that the chasing/closing footwork inherited from Wu-Hao taiji to Sun style would make plenty of sense to Xingyi guys. At least it makes sense to my Bak Mei.
My teacher tells me that Xingyi and Bak Mei have plenty of similarities in principles and ideas, but that they also differ a lot in many aspects that makes crossing over harder than one would think.
All of the above has of course nothing to do with Bagua.
Can you paraphrase your reply in a way that has a common interface with modern sport science methodology? Because most of that now ('vortex of energy') is simply impenetrable to me.
What, really, is the circle walking good for? I've never managed to grasp its utility.