>Unlike [my perception of] React or Angular, you can use Polymer a bit without going all in.
For what it’s worth, you can integrate React in your existing Backbone/Ember/Angular/etc app one component at a time. At my previous company, we have been doing this over the course of a year while shipping new features thanks to the interactivity React enabled.
Ryan Florence gave a talk about integrating React into an existing app: https://www.youtube.com/watch?v=BF58ZJ1ZQxY