I have
from my perspective they are quite different. As are some styles originating from different members of the yang family.
this is why imo its important to know or at least understand the history of what one practices.
In fact, Yang Zhenduo went to great lengths to differentiate between the types of movement exemplified in the Cheng Manching and his father's style; and he made it clear that he wanted to highlight essential requirements of his father's style. These stylistic differences can be summarized by the difference in interpretation over the Chinese word "sung." To the Cheng Manching stylists this word has always contained the ideas of being sunken, relaxed and empty. Yang Zhenduo, however, emphasized the characteristics of being open, extended and full.
http://www.taichiandqigong.com/yang_compare.php
as noted, dont quite agree with the authors conclusions
to expect someone to reach an understanding by studying the "source" seems like confusion unless one was already well versed in what they where currently working on.
ZMC had other influences, what source would one study from?
"In the room was a table where they had eaten. The two men were on one side of the table pushing hands. On the other side of the table was a wall, which was not very thick and made of wood (something like plywood). At that time Zheng Manqing considered himself to be pretty good. While pushing with Zhang Qinlin, he was very intent on trying to push Zhang over. Zhang Laoshi was just deflecting right, deflecting left. He then made a Ji, and Zheng Manqing flew - over the table and into the wall, which almost fell over."
Pu bingru (who was laughing while telling the story) said that the impact left a hole in the wall, and Zheng Manqing, after crashing into the wall, slumped to the ground. Everyone ran over, picked him up while asking if he was okay. Zheng stood up (a little shaken but not hurt - the outcome was not what he had anticipated) then went to his knees and said to Zhang Laoshi, "You must take me as your student." Zhang replied, "I just came for dinner. You demonstrated your form, and I demonstrated my form. This is not something I had expected." He told Zheng, "At the moment I do not have any time, and I am only here temporarily. I live in Shanxi province right now. If you want me to be your teacher, you will have to send someone to get me."
http://aymta.org/home/journal/zqlpt4.html
the styles themselves are quite different, enough to merit its own distinction by those that followed his teachings.
Is CMC respected ? what ever one wants to say one only has to look at some of his students who themselves went out to
prove the style.
Notable students (in Taiwan:)
Benjamin Pang Jeng Lo
Liu Hsi-heng
Hsu I-chung
Dr Qi Jiang Tao
Robert W. Smith
T. T. Liang
William C. C. Chen
Huang Xingxian (黃性賢)
http://en.wikipedia.org/wiki/Cheng_Man-ch'ing
one of his more noted students
Huang Xingxian (Huang Sheng-Shyan)
"Though they practice my (outer) methods,
not following my (inner) way they are not my students."
http://www.patrickkellytaiji.com/TEACHE ... gxian.html
On this site RSF many often talk of ZMQ, questioning his skill.
and yet, he had some very noted students who had practiced other MA prior to studying with him.
disclaimer: not affiliated with the style nor claim to be any representative of it, with the exception
that its was part of my own taiji path.