I like the double-space sibboleth. None of the reasons stack up, apart from "ordinary people use two spaces and professionals use one; I use one" :-) The one about "it creates a break in the flow of words" is excellent: that's *exactly* why I use two spaces :-D

Incidentally, I notice that the article is left-justified, which looks much uglier than two spaces ever does. I know it's another typographical convention, but it does aimed at writing in columns where the lines are short but the words are long - which isn't the case in this article :-) Still, better to carefully apply a rule where it's inappropriate than run the risk of people thinking you weren't aware of it :-D