Where to put plain object classes?

All it does is write a log message when constructed and then define a __get magic method that refers to the CodeIgniter singleton.

What's your point? You don't want to use the CI_Model class at all?

I could be completely missing something, but I wonder why I would want to have my DataObjects coughing up properties of the CI singleton object as if those properties were its own? What happens when my DataObject defines a property that already belongs to the CI singleton?

Why would it cough up CI properties?