It's a bit surprising that rank on HN and general traffic/mentions aren't very well correlated.

Its actually not that surprising upon closer inspection. The articles that were focused more general topics (The Cost of Cracking, How to Make it on Craigslist) were generally correlated, while the post that were more hacker specific (Minimum Viable SEO, Headphones for Hackers) did well on HN, but did not receive a lot of general traffic.

Very interesting post. How has the blog impacted your user growth? Given the effort involved in writing each post, has it been worth it in terms of growing the business?