Greetings..
I have no direct insights or information as to lineages of Taiji Ball training, either Chen or Yang.. i have trained with both.. Chen seems more strength related, yet it has some very useful QiGong sets.. Yang, as presented by Dr. Yang Jwing-Ming, is designed to develop principles and eventually phase out the use of the ball and return to empty-hand training, similar to silk-reeling..
I hosted Dr. Yang's Taiji Ball work-shop last January here in Central Florida, and we will continue again this January.. The training has been very beneficial, especially in coordinating the breath with movement.. The 8" diameter Cherry-wood ball i use weighs 5.4 lbs., and, after 6 hours of training with Dr. Yang seems like it weighs 40 lbs.. My daily work with the ball runs about 30-45 minutes and i find it has greatly enhanced sensitivity and my expressions of Peng..
My Chen training was minimal but the obvious focus was on a more external development of coordinated strength.. and, i have no issues with that type of training as long as it is in its proper perspective.. it has good benefits and shouldn't hurt progress as long as it is balanced with internal work, as well..
Both styles of Taiji Ball training are good and shouldn't be compared to the detriment of either.. in the end, it will be the student's intentions that determine how useful the training is.. even someone with only 3 or more years of Taiji experience under a qualified instructor will very likely "intuit" the benefits of this training..
Be well..
TaiChiBob.. "the teacher that is not also a student is neither"