I'm not sure that readers are necessarily turned off by small sans-serif fonts. It might be a matter of demographics, but Daring Fireball, which currently has an article on the front page of HN, isn't exactly struggling.
Is the font use on DF somehow different? I'm genuinely curious about your thoughts because I've always wondered if it turns off a significant number of potential readers.
Small sans is fine for web copy, but Futura really isn't. The typography at DF is excellent, with headings in Gill Sans and copy in Verdana. I favor serifs for web copy, but few stand up to scrutiny. I like Erik Spiekermann's Meta Serif[1].
I do differentiate. Though he mentioned the font face specifically, I interpreted his criticism to be about the font stack and size and thought he was equating all small sans-serif copy. Verdana is listed second in the stack and is the one that was used when I viewed the page.
