Oh wait, does this mean we should just be doing

```javascript
if (!model.get('id')`) {
    model.set('id', guid())
}
```

or

```javascript
if (!model[model.idAttribute]`) {
    model[model.idAttribute] = model.attributes[model[model.idAttribute]] = guid();
}
```

I'm a bit clueless regarding non-standard backbone ID attributes.