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.
Github pages can only run builds of plain jekyll sites with no plugins. Netlify will work for pretty much any static site generator (right now we support ruby, node and python).
You can also trigger new builds without pushing to Git (essential for pages like https://www.staticgen.com that grabs data from somewhere else than the Github repo).
Apart from that there's hosting features like:
SSL for custom domains
Redirects
Rewrite rules
Fine grained header control
Lossless image compression
Automatically moves asset to content addressable URLs on a cookie-less ___domain with far-future expires headers
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.