One gotcha: This only works if the class you're working on actually implements that method itself. If it inherits the method from some superclass, this won't work as expected.

Due to that, I personally prefer poseAsClass: because it allows you to simply override an existing method, but at the same time reroutes all future requests for the base class to your subclass. Of course, poseAsClass: doesn't retroactively change objects created before the posing happens, but I rarely need that.