I've read of many failures (Maybe 10? - the problem affects most Cessna single models as well as the 336/337) but I have yet to read one where the airspeed at time of deployment is recorded or mentioned.
Here's an interesting link - it includes two descriptions of pilots successfully flying Cessna singles with asymmetric flap deployments. So it seems the answer to the OP's question is "Yes, it can be done." It also includes examples of flap failure on *retraction,* which I hadn't heard of earlier.
http://cessna170.com/forums/viewtopic.php?f=2&t=6608