I like how in Demi-chan wa Kataritai the demis still possessed some extra race/species specific skills or abilities, however you'd call them. This story suggested the demi-humans are mostly lacking such things, so the differences from humans are mainly cosmetic. Although Izumi said she has excellent hearing. I'm starting to think succubus-sensei never could fly, though, even back when she still had both wings. Maybe her mother couldn't either.