How Much Client Side JavaScript in Rails 4?

Articles and Quick Summaries:

• RailsConf 2013 Keynotes: Rails 4 vs Ember.js: DHH on server side vs. Yehuda on the client side.
• Improving performance on twitter.com: Twitter's retreat from client side js.
• How Basecamp Next got to be so damn fast without using much client-side UI: DHH on the Rails features the preclude the use of client side js.

Why Discourse uses Ember.js:

Ask yourself how interactive your web application needs to be. On the less interactive side of the scale, there are huge wins with server side rendered HTML. The more interactive your application becomes, the more you’ll benefit from a client side MVC framework.