Re: Internal power in tai chi chuan
Nice description. William Chen is a good source for learning (one) perspective on internal power. I'd venture to say that his understanding of internal power is developed more from his own study than on what he learned specificially from Zheng Manqing. The separation of ribs/intercostals from abdomen is interesting and may be similar to Fujian Baihequan (White Crane) shenfa (body usage), which influenced a younger fellow student of Zheng Manqing, Waysun Liao (teaches in Chicago), who studied Baihequan and later taijiquan in Taiwan under Zheng Manqing.
It's a good practice and Mr. Chen is a well-respected teacher. Both his son Max and daughter Tiffany compete in MMA, although to what extent either uses taiji in tournament fights is hard to say.