Automatically update model with filter

First of all, I'm using Firebase, or more specifically, EmberFire. I'm making a simple chat app and everything was going along swimmingly, until I attempted to limit the number of posts that are first fetched.

I had

// routes/index.js

import Ember from 'ember';

export default Ember.Route.extend({
    model: function() {
        return this.store.find('message');
    }
});

and I changed it to

// routes/index.js

import Ember from 'ember';

export default Ember.Route.extend({
    model: function() {
        return this.store.find('message',{
            orderBy: 'timestamp',
            limitToLast: 10
        });
    }
});

With the former, as soon as new messages were posted, they would show up in my other browsers. With the later, I have to refresh the page for them to show up. I believe this is because the first returns a DS.RecordArray while the second return a DS.AdapterPopulatedRecordArray, but I'm not sure how to fix it.

How can I fetch the last 10 messages, but still have new messages automatically added to the model?

DEBUG: -------------------------------
DEBUG: Ember      : 1.11.1
DEBUG: Ember Data : 1.0.0-beta.16.1
DEBUG: Firebase   : 2.2.5
DEBUG: EmberFire  : 1.4.4
DEBUG: jQuery     : 1.11.3
DEBUG: -------------------------------