The Scheme is a great way to Punish Low Defense Models the trade off is most have Armor but hitting them is worth it. Getting to Change Seamus, CCK, and a Belle Together is a lot of actions back to back Like I don't Know getting Treasure not only picked up but back to your own Deployment zone Fast. He isn't for everyone I agree but I still think he offers more to a crew than other Options I agree if your Running Hanged or Syblle you should probably use a Grave Spirit but even then I still like him over the spirit.
Avatar Seamus is fun but Not Needed and for a Master that has a small Cache The avatar is not worth it if you intend on smashing in a lot of High SS cost models like Hanged and Yin. Just my thoughts.
It is the Internet and people will Disagree. I am not saying what you are doing by not running CCK is wrong just Defending the Model and the use of Doxies.