Hmm, very good question. If anything I would expect the gramma to pick on the swissguard. It's established and Liopropoma are pretty shy. How big of a tank?
Sorry, I should have posted that. Its a 90 gallon tank. It already has a scopas tang, tailspot wrasse, bangaii cardinal, lawnmower blenny and midas blenny. I was mostly worried about the gramma though. Mine doesn't seem to be too territorial (unless I stick my hand in there) but none of the other fish are the same size/shape as the gramma.
I've been able to keep swiss guards and royal grammas together without problems. I have also kept swiss guards with black cap basslets without problems. I was also able to keep a royal gramma with a black cap basslet without serious fighting.
Mitch