Niles, your suggestion is really interesting and powerful! 
I’m agree with you about the Multi Instruments in Studio One 3… unfortunately it’s very limited, and it’s just container at the moment. There is no way to open just one Kontakt player with few libraries, and to switch them inside the player… The only way to switch the libraries is to open separated Kontakt for every library, and to use automation on bypass, but it doesn’t work properly yet…
If the guys from Steinberg decide to create this feature in Cubase /Nuendo, I would prefer to be more like Orchestral Tools C.A.P.S.U.L.E.
Such MIDI track would save a lot of space on the timeline, and would bring it more closer to the orchestral stems.
They also have to implement drag and drop (from everywhere), the modern way of loading instruments, effects, audio and video files, like in Studio One.