Middleman is awesome and very proven in the field. There's a lot of cool sites out there made with it.

At Netlify (https://www.netlify.com) we're building a static hosting service with integrated build automation that's perfect for projects built with static site generators.

With the right tooling this approach to building websites can be so much more efficient than traditional dynamic sites, and it solves all the issues around security, performance and scaling costs that plagues WordPress and Drupal sites.