Hi there.
I have this question, I'll esplain why, I have a job where I will have to render A LOT of images that will be exactly the same, except that I will have to change some logos and some colors, those colors won't affect too much to the illumination (well, the may affect but it's not important if I change them and it's not perfect) so to avoid having to render 50 images with 50 different textures I wanted to render the elements without the "color" element and having the color in a spearate element, this way I could be able to replace the texture of the object with the logo in comp using the UV channel and skip those additional renders that could take A LOT.
Check the attached picture, I think it's a better explanation, you can see th teapot with face as the rendered one, and you can see how I changed the teapot texture with a bricks texture in compositing, I did not have to re-render anything, just change the texture in comp.
So it's possible to do this right now?
Cheers.
P.S.: ignore the gamma shift in the result and the different elements, it's just because I made this explanation picture fast and that was not an important thing.