In almost all normal cases? No. In testing, I found the following case you can test in the console that should report no method content_changed? for nil (it should do the same in the base unmodified code):

```
test = ActiveFedora::Base.new
class FooAdaptation < ActiveFedora::Base
  has_metadata :type=>ActiveFedora::OmDatastream, :name=>'someData'
end
test.add_relationship(:has_model, FooAdaptation.to_class_uri)
test.adapt_to_cmodel
````