Originally Posted by
hairnet
Please don't perpetuate this exaggerated fear of the front brake. Learn to use your front brake (wow, learning to correctly use your equipment) and you will be able to "slam" on it without flipping over.
Slamming on a rear brake will initiate a skid, which will only cause you have even less control over your bicycle and increase your likely hood of crashing.
+1
http://sheldonbrown.com/brakturn.html explains this very well, too.
To the OP, just a front brake is perfectly fine to stop your single speed bicycle promptly and efficiently,
provided it does not fail. The risk is up to you.