I mentioned that as an advantage in one of my other comments. An advantage both ways, because it depends on preference. I have the same preference as hansvm: I would rather see the dangling dash at the end of the line, so I prefer putting spaces around the dashes. Having the entire word-dash-word structure move to the next line feels ugly to me. As with most things, de gustibus non est disputandum. (And also, quidquid Latine dictum sit altum videtur).