I know this is asking for generalities, but how does Okinawan Goju Ryu compare to Japanese Goju Ryu, specifically from the YAMAGUCHI Gogen Sensei lineage? I asked because I like Sensei Peter Urban's books and tend to think about Japan style Goju Ryu when I think of the style. But I also read that Yamaguchi Sensei didn't study that long with Miyagi Sensei, and that there has to be lineages of students in Okinawa who studies for a longer period.