Good points Todd. I too have found myself imposing schedule date in order to attempt to force an action or project and end up over booking every day. I too have been leaving my system daily feeling I have failed in some manner. I never really thought of them as 'fake due dates' but they really are.
I'm still stuck in trying to work with priorities since they do come into play after context, time available, and energy but maybe I should reconsider. The first thing I am doing at work is remove any non-deadline scheduled dates and try to get back to the a more pure GTD solution.