This post is so old, but I am new here so let me throw in my 2¢. First about pull-back. I truly believe that it is used as a training tool. Once a karateka truly understands Sanchin ( if you practice it for many many years) you can transfer the knowledge that you learned from the push-pull technique, to gojuryu's hard soft technique. What I am saying is that you learn how to apply the same concept using sanchin rather than push pull. Now onto hand position. Don't forget what Tatsuo Shimabuku said when he was once asked by a group of karateka sitting a table drinking. He asked them which of the bottles on the table was the best. They argued that this or that one was the best, and then he replied with a simple yet well thought out message, "all the bottles were good. All of them served a purpose: to hold what they were intended to." That being said, I prefer to use what we train. I am fortunate enough to train with some people that know very well the capabilities of the body, but each style could argue which is better. Next time you want to test the difference have someone hold your hand in each position while trying to push them away. Which position do you feel stronger in?? I would argue that with your fist at you hip you are able to use your entire body to push your fist forward, whereas the higher you place your fist, the more you tend to use just your arm.