Are we allowed to push non DS.Model data into the store?

With http://ift.tt/1zOPx96 are you only allowed to push DS.Model data into the store?

If the latter, can I define a custom model (one that doesn't inherit from DS.Model) and that should work fine?

I'm looking at: http://ift.tt/1w6LVE9 can't find any indication anywhere.

Any implications with this approach? Is this an anti-pattern / convention buster? Or common practice?