Testing automatic inclusion of GH geometry with custom materials in the render process. This can be done using the [Custom Display] component in next weeks Serengeti WIP release:
Be careful when baking though, all too easy to end up with something like this:
Ah, that brings up an old wish: The ability to purge similar materials and also to drag a material on top of another to both merge those materials and their assignments. Those are very handy tricks to tidy up a file.