They've gone back and forth about the invisibility stuff over the years. I remember Byrne saying in an interview that he thought it was stupid, so he avoided using it during his run. And at least one of Kurt's Marvel Handbook write-ups tried to pass it off as just "his dark fur makes good camouflage" rather than being an actual power. I like the idea of tying it into his teleportation, which makes it seem a little less random.