The bindings simply extend the Collection object and override certain methods on it (add, remove, etc.) to do the corresponding Firebase operations.
We did run into a few relatively minor issues; for example when doing a smart update to a collection, Backbone seems to trigger a remove event immediately followed by an add event for a model that hasn't changed.
We still have more work to do with the bindings (we don't have a Firebase.Model object for instance), but I don't expect any major roadblocks. All in all, piece of cake!