For what it's worth, we are about to start a sprint to rebuild the customer-facing side of a Rails application using EmberJS. I will more than likely post a walkthrough of the experience. We have worked a lot with both Backbone and Ember. They are very different tools and I don't think it's fair to compare them directly, but I am definitely a big fan of Ember. I even have a t-shirt!

If you are interested, blog.chriswinn.com is where I will end up posting the Ember walkthrough - probably in the next few weeks.