I've always debated the use of C-AF over S-AF.  Someone on the Olympus Facebook QA session asked which is better and Olympus actually gave a good answer.

Question:

I wonder about the accuracy of C-AF vs S-AF. In most cases, at least in my experience, S-AF seems more accurate. I generally use a single (center) focus point using this camera. What are your thoughrts, opinions?

Answer:

I'll give you an example of when C-AF is a good choice however, anytime you have a moving subject on a solid color background like a bird in flight against a blue sky or a tennis player on a green turf, etc. In this instance try turning all AF targets ON and using CAF, you'll be surprised at how quickly the camera can focus.

people coming towards you is the best example I can think of