After much experimentation, 3 of my 4 bikes now have half-clips, and I really like them. Easy to flip and so easy to get out of, yet they have enough grab to hold my foot to the pedal. I wear a low-profile driving style Adida black sneaker and they slide right in. Basketball style sneakers are to bulky however.

MKS makes some nice ones and go for about $18 on e-bay...