The POCS method has proved to be one of our more succeessful methods.  The computation time is long, but pales in comparison to the Bayesian method.  Typical runtimes were on the order of hours - certainly doable on the machines that we had access to.

This is the one of the 5 LR images that we began with (128x128 pixels):

                                .

And this the SR image that we obtained (256x256 pixels):

POCS is clearly the algorithm that produces the best results!