"theoretical kung fu"?? Everything is a theory untill its tested & used by a serious practitioner; Including your book.
The information therein is taught by traditional schools, its just that sometimes it is overlooked or under-practiced by the practitioners of the arts.
Fact is, they are all very awsome & which one is best is very hard to distuguish. This is a fact that I am quite proud of. The art that I chose was not of which one Was the "end-all-be all" system, Its the art that fits my personality, is traditional, and Works.
~BTL