i think that's not the issue.  that is, yes, Tone Mapping is a color correction technique.  so it doesn't make sense to use it and GC, i'm sure.  the issue is if you're still doing calculations after the shader is produced,   the IDL calculation is, like all other calculations, linear.  if you feed it non-linear information in the form of your shaders, that's a problem.

basically, these means you can linearize your input, but you shouldn't correct anything but the whole render. you could do that several ways, including bagginsbill's artistic lens trick.