Maybe I'm weirdly old fashioned, but I try to stick to ascii whenever possible - which means whatever character is stuck in the middle of this sentence. Ditto for the ellipsis, since it's not like three trailing periods at the end of a sentence can be mistaken for anything else...
I use an old convention for approximating em dashes in ASCII by using two hyphens, set apart from surrounding words by spaces. Typographers might shudder, but I find the meaning clear -- its presence signifies the same sort of rhetorical devices that the article talks about. The surrounding spaces serve to make the deliberateness of the punctuation more obvious.
In many rich text generators, an em dash is often made with three hyphens, but for as-is plain text, I find three hyphens excessive. In my opinion, most of the usage of the en dash -- the rival, shorter dash -- occurs in situations where you wish to connect, rather than set apart, so while typing in ASCII for the things you'd use an en dash for, a single unspaced hyphen suffices.