Shorin-ryu is probably the least consistent of styles when it comes to what is taught and, if I recall correctly, the reason is that there was no "curriculum" before modern karate that had a specified set of kata that everyone had to know to make a particular rank. You were simply assigned kata based certain attributes, such as body type, etc. And that's reflected on how the different branches of Shorin-ryu (headed by the students of Itosu) differ so much from one another. I'm not sure if Chosin Chibana knew or taught Seisan, but I know that Nakazato didn't teach it. But Chotoku Kyan DID. On another note, I'm not sure of Kyan taught Naihanchi Nidan and Sandan, but Shimabuku didn't. So there's another example.
Shotokan's Hangetsu is unique in that you don't kick in every direction like you do in Shorin-ryu, but it's definitely closer to Shorin-ryu's version than the Goju-ryu and Shito-ryu versions.
