I believe that Sensei and Master Hsu met when they were both demonstrating at the same event in 1979.  I have had the good fortune to have met Master Hsu and participated in some of his workshops many times.  Master Hsu and Sensei shared their love of good food and martial arts.  He was one of the few people Sensei regarded as a true master and Sensei also helped him with two of his books and many of his articles.  I can say without a doubt that Master Hsu is a true teacher.  I stumbled upon a series of interviews with him.  I haven't watched all of them but I am sure they are full of good information regardless of the style of martial art you practice.  Enjoy!