Actually Mabuni also trained under Kanryu Higashiaonna, at his friend, Miyagi's, suggestion. But he also trained with Miyagi and Shito Ryu reflects those traditions.

From my humble perspective all of those versions, Tou'on Ryu, Goju Ryu and Shito Ryu fall within my Seisan template along with the rest.

But I suspect that the Tou'on Ryu version reflects the older, simply because it remained a private practice with fewer involved in its transmission.

Of course that's just an opinion, and all of those versions are equally yet differently applicable in my book.
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