I think its great that you can re-run the conversion for only selected mats. I know I'll end up using that a lot.
Also from the original post "even later we want to add the ability to push some specially prepared mesh light objects directly from the plugin into the scene (lets say, add a light bulb, add a flashlight as parent to a camera, add a soft box, add a spotlight, ...)"
It would be nice to see added eventually. This is a feature that reality offers and I ended up using it a lot because it was useful to have some prefab pieces that you can work with. And while it may be a relatively small thing, it will still be a comparison point for potential buyers.