I've been waiting for their Polaris edition for a while now. It looks like it is still not released. But am gonna learn Emberjs one of these days. It will be my secondary framework for projects.

We need more LTS versions of dev tools like emberjs, django, node etc. And am a fan of their RFC process as well. It looks like this is the framework you use if you want to incrementally improve stuff without having to go through radical shifts between versions.