I am no longer "in" sd but I still practice some of the material I learned there...
I did not learn any of the external sd material only the internal. Of the internal I learned I think "yang 64" was taught best.
I have be lucky to meet and train and compare with tai chi CHUAN people all over the world. I travel ALOT. When I travel I seek out what ever martial artists I can and get as much exposer as I can to other styles. In comparing the tai chi CHUAN that I learned from my sd/csc teacher I have not had people call my practice into question.