Made me look it up in my own environment. I had already set up a custom incantation for em and en dashes, although I really have no idea when to use the latter instead. Actually I never used to use em dashes, but now I do. I'd much rather deal with people who can intuit the quality of writing rather than relying on such blunt heuristics.
Discerning readers do not stop at the em dash. At least, I don't.