I had weird/wrinkly results on a few custom characters I had built using merchant resource morph sliders and then baked into single character morphs. I think that the problem ended up being that the script was not working well on my characters that had required adjusting the rigging with the joint editor and an ERC freeze. I tried going back to my original obj file, re-importing that, NOT adjusting the joints, and making a new character preset with that new morph. Then the conversion to G9 went well. Still no luck with mats though, but I need to look at the manual a bit more.
In short - it seems to work when I feed it GF8 characters that are default G8F size, and not work when they are taller/shorter and needed joint editor work when creating them.