Actually when I read through all of the threads on clipless pedals, one of the prime advantages of the platform egg-beaters, that people cited over and over again, was that they were fine when used with regular, non-bike, shoes. Now, this isn't obvious to me when looking at the pedal. At the least it looks like you'd need a shoe with some tread depth. And you'd want a shoe with a sturdy sole, or else you'd feel the "hot spots" where the metal brackets were pressing on the bottom of your shoe.

Some of the egg-beaters have pretty large platforms, like this one:
http://www.crankbrothers.com/acid.php

The big complaint about the one-side clipless, one-side normal platform pedals was that the weighting of those pedals is such that the clipless side rotates to the bottom side. So that much of the time when you unclip, you have to use your feet to flip them over and then catch it before it flips again. My take on the comments I read about this design was that about 2/3rds of those who had used such a pedal didn't like it and didn't use them again on new bikes.

I was leaning in that direction until I read all of those complaints. I would estimate that the percentage of people who complained about egg-beaters was about 1/10th that of those who complained about the one-side SPD pedals.

As always YMMV.