Mr. Torres,
I appreciate your curiosty. Certainly some of the differences between Chojun Miyagi's Goju-ryu and Gogen Yamaguchi's Goju-ryu can be attributed to differences between the Japanese and Okinawan cultures and even to the personalities of the men themselves. And clearly there are differences in training methods (i.e., the presence/absence of hojo undo, methods of kumite training, differences in the patterns of kata). These are certainly all valid points for discussion, but to me they are academic. In my opinion, the most significant differences are deeper than that and cannot be understood without having been felt.
You may find Chuck Merriman to be valuable source of information. He is a serious, knowledgable karate-man and was a student of both Peter Urban and Eiichi Miyazato. His contact information is on the website I posted above.
I wish you luck with your research.
Regards,
Dale Horton
"It is not the critic who counts, not the man who points out how the strong man stumbled, or where the doer of deeds could have done better. The credit belongs to the man who is actually in the arena; whose face is marred by the dust and sweat and blood; who strives valiantly; who errs and comes short again and again; who knows the great enthusiasms, the great devotions and spends himself in a worthy course; who at the best, knows in the end the triumph of high achievement, and who, at worst, if he fails, at least fails while daring greatly; so that his place shall never be with those cold and timid souls who know neither victory or defeat." T.R.