nitshift, hello my friend,

I can't really tell you about that. Being a music and lyric writer, I don't really ever do one or the other. The closest to it is a thing that has happened to me a couple of times. With every demo I do, I get a "track mix" which is the music track with no vocals. Since my demos are pretty much radio ready, they can be inserted into a scene or background of something easily with no vocals.
It is another reason to do good demos. You might find them in a place you never thought about. I have learned that instrumentation can take a song into an entirely different realm so that is a consideration.
What I would suggest you do is what I suggest to anyone. Find out someone who does what you are talking about (probably on these pages) and find out what they do. These pages are all about information, different perspectives. In my experience if you ask a question in the right direction, usually it will lead you to someone who knows the answer.
You might ask Mike Dunbar, who does things with music tracks more than I do.

MAB