I definitely hear your concern. But on the flip side, I decided to take the plunge with Ember rc2, and I've had to deal with very few breaking changes. And of the breaking changes, they were very minor. I didn't have to re-architect anything. It's been very pleasant, and the amount of value I've been able to extract out of Ember has been tremendous. So much so, that I've held off being a huge advocate since I consider it to be a competitive advantage.
Ember Data, on the other hand, hasn't been ready. I also took the plunge with Ember Data with 0.12, and it turned out to be a mistake that's still looming over my head. (I think I would have been better off with Ember Model, or EPF which didn't exist at the time. Yes, I understand when you're new to the ecosystem, they all sound the same.) I think this has been a big part of where the confusion stems from. People who are new to Ember don't realize that Ember Data is a completely separate project with its own status.
Please correct me if I'm wrong, but as far as I understand, there's no equivalent of Ember Data in Angular. Am I right? If that's right, then of the little bit you've said, it seems like you've run out of excuses not to use Ember :)