I am using the same type because, from my understanding, it's given that down and up type are compatible at this point and thus the same here. This means I can just provide the up type for both input and output, as the branch_connect_down function already tested for format compatibility between MFT/Source and EVR.
Sure and it's very possible that it's the right thing to do, but I don't think you need to move the copier creation for that, you could just do the same where it's currently created.