When asked, my instructor and Stewart Olson, will tell you that our style of Tai Chi is Yang style. I've studied under another Yang system though and I was surprised at the differences. In fact, I really didn't understand how they both could be the same system! Then I read an old book by Robert W. Smith and Donn Draeger and in it, Robert Smith breaks down CMA for the western reader for perhaps the very first time. It is interesting to note that Smith was also a student of CMC, by his own admission, and he considered Chen Men Ching to be an excellent martial artist. I wonder if the differences in the systems can be seen by going back to which Yang trained who. Forgive me if I mangle this, but I don't have the book infront of me, but Yang Lu Chan had two grandsons that survived the murder of his family. Both of these men carried on the tai chi tradition. Yang Cheng Fu changed what his grandfather taught him though, taking out a lot of the silk reeling fa jing and making it more of a hidden and healing art. Yang San hou, on the other hand, kept the silk reeling and taught the applications more directly. Basically from my vantage point, both are Yang, but they are interpretations. With Yang San Hou you can see the effectiveness and applications readily. With Yang Cheng Fu, it takes an instructor to point them out.
All this about knee problems...in class we NEVER put our knees over the line of our toes. Perhaps that is TT Liangs interpretation of CMC.
upnorthkyosa