Sorry i get offended when people use my favorite coral and the word "invasive" in the same sentence. But honesty I wouldn't consider them invasive by any standard.
I agree it isn't an invasive amount and he asked would it become a problem. I like them they're quite colorful. I once heard a guy in a thread say he had an Utter chaos "problem" and they were growing everywhere, I laughed pretty hard they were the best looking chaos's I'd ever seen.