I have a DS.Store which uses the DS.RESTAdapter and a ChatMessage object defined as such:
DS.Store
DS.RESTAdapter
ChatMessage
App.ChatMessage = DS.Model.e
My reading of the source (DS.Store.find) shows that what you'd actually be receiving in this instance is an AdapterPopulatedModelArray. A FilteredModelArray would auto-update as you create records. There are passing tests for this behaviour.