I found this very interesting. It has been many years since I learned Xing Yi, but I seem to recall my sifu being a stickler for functionality. He experimented with boxing footwork and the monkey footwork of our mantis system. I haven't practiced Xing Yi a lot over the years but when I do I usually stick with the patterns without the modifications made by my sifu. I suppose if I were teaching it I would use and teach those modifications.