Hello,
These are just some rambling thoughts feel free to disagree.
first the influence of Shotokan on Chang Hon Tae Kwon Do is undeniable. Compare Won-hyo with what is in Japan called Heinan Nidan.
(Okinawan Pinan Shodan).
But it isn't just cut and paste.
Emphasis comes to mind. Besides more acrobatics kicks you have Toi-Gye with six Yama Uke in a row.
When I saw someone drop to the ground and round house kick in a high level Tae Kwon Do Tul I thought well that is unique. Then I saw someone doing Unsu and I realized just because it is not in Karate Kyohan doesn't mean Shotokan doesn't have it.
A couple things I think might not be in Shotokan are the straight out to the side shuto at the end of Do San and the stepping feet together, not across to attack the other direction. Occurs a lot but end of Won Hyo is a good example so even if Shotokan does this the emphasis is stronger in Chang Hon TKD.
Interested in your thoughts,
Len McCoy