It would be good to have a Midi Channel as an attribute of a note or a voice in the notation editor (and piano roll editor as well).
This allows for sending notes to specific instruments or parts in a multi-instrument track or Kontakt-like VST without necessarily having to have the notes in separate tracks or instruments. There is a Note Inspector for notes in Piano Roll view where this attribute would be showable and editable. This note inspector should be available in Notation Editor as well.
Probably not likely to get implemented any time soon as there are more important features, but it should be implemented at some point.