I re-launched my site last week:
Used Sage for the Gulp workflow and theme wrapper, but no Bootstrap! Instead, I built it as a SPA with WP-API using vue.js and their other tools, vue-router, vuex, and vue-resource.
My first "real" SPA and my first Trellis deploy to Digital Ocean. Once I upgraded to the latest Trellis (it took a couple hours to rebase, it had been awhile), Trellis worked flawlessly. And I don't think I can go back to shared hosting.
Used Modular Scale for the type on this one. It scales up and down well enough by default that it probably saved tens of KB in additional CSS, and the site looks readable on large screens as well as small.