It's so nice to see someone being practical about this issue, rather than 'fundamentalistically' insisting on no spaces around m-dashes. Styles are not set in stone, they have to change with the medium, and I bet there was a time when this was a new and revolutionary style, too.
I have a line wrap issue of my own. Ellipses styled as on typewriters. You know; space-dot-space-dot-space-dot-space . . . You see it often in fan fiction, especially in older fandoms with older writers.
Unless you put in non-breaking spaces in the html code, they wrap! And it's ugly. Why do people still insist on them? Either use a code formatted ellipsis or even go as far suggested on Wikipedia; three dots without spaces. Simple, and works every time.
Phew! felt good to get that off my chest
