If i disable writes to the color buffer via glColorMask(false,false,false,false), does anyone know if the majority of the drivers out there are smart enough to bypass lighting and texturing and whatever other calculations could change a fragment color?

You’re asking, not for one card or driver to be smart, which I am sure that there is at least one out there… but all of them to be smart. You’re asking a lot in my eyes, honestly, I really don’t know, but I would bet there’s got to be one card that will not be that smart. My buddy Murphy says you’ll prolly run afowl with this one card/driver. I would disable lighting and all, just to be sure.