The static assets are actually served by nginx. In cases where some page data is dynamically generated by Rails, it's nice to keep both pieces of code together in a mono-repo. That said, when I recently extracted a Backbone app from the Rails codebase (retrofitted Grunt.js), I decided to ditch the public/symlink approach and split the app over 2 subdomains. What I find now is that I like the mono-repo approach, and would be fine with cramming both codebases together, while having granular and global deployment scripts.