For ideal agents, absolutely. For things like humans... Have you looked at the models in "Do Sunk Costs Matter?", McAfee et al 2007?
EDIT: I've incorporated all the relevant bits of McAfee now, and there are one or two other papers looking at sunk cost-like models where the behavior is useful or leads to better equilibria.
I just finished the first draft of my essay, "Are Sunk Costs Fallacies?"; there is still material I need to go through, but the bulk of the material is now there. The formatting is too gnarly to post here, so I ask everyone's forgiveness in clicking through.
To summarize:
(If any of that seems unlikely or absurd to you, click through. I've worked very hard to provide multiple citations where possible, and fulltext for practically everything.)
I started this a while ago; but Luke/SIAI paid for much of the work, and that motivation plus academic library access made this essay more comprehensive than it would have been and finished months in advance.