This seems to be one of those many instances where I would trust more results obtained using one of the principles of experimental economics: When asking participants to do things that require effort, provide a reward that correlates positively with their performance on the task.<p>In addition, let's say there some validity to the result that two spaces provides a slight benefit to a subpopulation of readers. Does it matter? Is what is true for the general population true for your readers? What is the cost to YOU, the author? Maybe through self-selection, most of your readers are those who are comfortable with single spaces.<p>I typed a lot of papers a mechanical typewriter. Then I started using WordStar. In either case, I learned myself and it never occurred to me to leave two spaces after a period. No one around me complained. Nor did I ever see anyone use two spaces after a sentence. And, I was around typewriters a lot with a journalist father and a secretary mother.<p>I did not learn about this rule until I came to the U.S. for grad school to witness the horror of people hitting the space bar twice after each period on WordPerfect.<p>Apparently, being completely oblivious to the alternative was not much of a hindrance.