Recently, in a webpage discussing Sun Lu Tang's contribution to chinese martial arts. Shifu Mancuso discusses Sun Lu Tang's efforts:
Sun Lu Tang created his Open/Close form of Taiji in 1918. He incorporated his philosophy and the arts of Xing Yi and Bagua. Sun had started his training with Li Gui Yun at the age of 12. Next he studied with "Devil Hand" Guo Yun Shen. Next he learned Bagua from Cheng YanHua. Hao Wei Zhen taught him Hao Taiji. From all this Sun decided that Xing Yi was characterized by its character, Bagua by its unification and Taiji by its softness.
By the "unification" inherent in Ba Gua, I guess he meant Ba Gua unifies movement by combining stepping, with hand, arm and limb position all at once into an appropriate application.
It is interesting to note that the idea that Hsing-I, Ba Gua and Tai Chi constitute the major Internal Arts of China is not necessarily agreed on by all Chinese martial arts practitioners. It is Sun Lu Tang's conclusion, many Chinese perceive the whole field differently. While I'm rambling a bit here, its always fascinating to me how differently the first palm is done by different practitioners.
Thanks for the videos.