I went for Shimano SL50's on the Synapse, MTB cleats and shoes as I need to be able to walk around in them a bit. Expected to be terrible, but got used to them very quickly, they unclip in either direction, but I seem to have picked a movement and stuck with it. I always clip right first and pull away left on the floor, unclip left first. I've commuted in with them, my right foot is clipped for the whole ride, left in and out for some junctions and traffic. It's quickly become 2nd nature although I don't miss them when I go back to the DMR's on the Sirrus.
I've had one close call when the car in front stopped quicker than expected and I spent all my brain power on downshifting and breaking. I realised at the last minute I hadn't unclipped and yanked my foot clear before I toppled over, I may have been saved by the very forgiving nature of my particular cleats. Was a handy adrenalin burst for climbing the hill I was at the bottom of though :-)
I like them least on steep climbs and at the moment my distrust of being able to clip out quickly has meant me stopping on some steep climbs I might have done in one on flats.