technically eggbeaters are clipless pedals, since they secure your foot without toe clips, just fyi
the 5050s i've heard are good platform pedals (even though those who ride hard, i.e. trials, jumps etc say the colored plates start to come lose) but i don't recommend riding platforms on a fixie, especially without brakes. that said, i've done it, i just don't recommend it.
have you looked at the mallets? that is what i have, you can ride them like platforms with no problem, then when you are ready to go clipless you don't have to buy new pedals, and you can always go back and forth.