Grok vs. Django for RESTful API?

[TG]

Just hoping to get some opinions: Grok vs Django for REST? I've started evaluating TastyPie with Django. Is there something similar for Grok?

I'm working on a project that will mostly be mobile-app based. Though there will be a web interface, the mobile part is more important to us. Our data model is pretty straight-forward so far (it's a social networking type app), but may become a bit more involved if we begin to add information/event streams.
So finding a framework that works well with a dynamically changing data model is somewhat important (hopefully we won't change it too often). Having a good security/authentication/authorization framework is important too.

I consider myself pretty strong with Python and other languages, but web programming is new to me. I'm comfortable though with HTTP/SQL/etc.