This. My team is currently making a pretty big bet on the future of Ember, and so far it's been amazing (coming from Drupal + Rails templates with jQ everywhere). Back-ends are in Rails API. Works great with Ember and you don't have to make 47462685868 decisions to get started with a project, make all the tooling play nice, then teaching the rest of your team how it all works. We're currently in the process of establishing a "paved road" for CI/CD for Rails API back-end + Ember front-end apps.
Deployments take tens of seconds. Roll-backs take single-digit seconds. Previewing not-active-but-uploaded versions of the UI is trivial. Everyone does the same exact thing when they deploy (or throw it on Jenkins for even more fun).
Ember CLI is also awesome, and Ember CLI Deploy is damn cool once you get it: http://ember-cli.com/ember-cli-deploy/docs/v0.4.x/lightning-...
Deployments take tens of seconds. Roll-backs take single-digit seconds. Previewing not-active-but-uploaded versions of the UI is trivial. Everyone does the same exact thing when they deploy (or throw it on Jenkins for even more fun).