The Changing Gate Block

I was watching a video of a teacher doing Seipai kata recently. It was nicely done--strong, crisp movement, precise. But when I watch kata there are a few I suppose somewhat subtle things I try to see, and for this kata one of these things is the "changing gate block," for lack of a better name. I find this a fascinating "block" or receiving technique. It can be found in Seipai and Sanseiru. Goju-ryu generally blocks and attacks almost simultareously. This is also true of the "changing gate" block, but the uniqueness is that one blocks and attacks from the outside and then moves inside almost immediately. Almost all the bunkai shown in Goju classical kata have three parts to them--the receiving technique, often containing both a block and attack, the bridging or controlling technique, which moves in much closer to the opponent, and the finishing technique. I would say that this is nowhere more apparent than with the "changing gate" techniques, except that there are many teachers--some quite "big" and with a large YouTube following--that interpret these moves in kata quite differently. But the "changing gate" is quite a fascinating technique and wonderfully versatile when it comes to employing kata variations--that is, connecting to other controlling and finishing techniques from other kata. Of course, the illustrated techniques here are just the beginning of the "changing gate," the entry technique showing the block and attack from the "outside"--the first from Seipai and the second from Sanseiru. The technique that follows each is the inside technique. The "change" occurs inbetween them, as is so often the case in Goju-ryu. One should always pay attention to the spaces in between.
Of course, there is another significant "problem" this brings up and one I have been wondering about for some time. The "changing gate" block shown above--Sanseiru kata in the Shodokan (Higa) school using open hands--is not done apparently in Meibukan, Jundokan, or Shoreikan schools, at least from what I have seen on YouTube. Why of these major Goju-ryu schools is the Shodokan version so different? Higa Seiko sensei was the senior student under Miyagi Chojun sensei, but the teachers who started these other kans studied with Miyagi sensei also. Why the difference? It's not done in the To'on Ryu version either. The "changing gate" block seems so fundamental to an understanding of the end part of this kata. It's like the "sun and moon block" in Seisan that seems to be unique to Shodokan. Why such significant differences in kata?