[ebryn]

Actually, it doesn't "force" you to use get/set. You can just POJOs just fine w/ Ember, but you won't get property observation or unknownProperty support.

I also question your assumption that Object.observe will be as fast as Ember's observation system. I wouldn't be surprised if it was several times slower.

Object.observe also doesn't support array observation, which is something we support in Ember.