Using Tv and Center-spot AF, I've never had any problem catching action pics in-focus. Any lack of focus has always been my own inaccuracy in pointing that spot.
I don't use center, that makes for quite boring wedding shots, and sports shots. 
I am not saying this was the fault of the camera, nor is that the point of the replies. Sometimes 1.8 won't cut it, nor will it give you any latitude for mistakes. Thus if you are going to shut the lens down a bit, let's say f2.8, then why not just keep shooting the 70-200 f2.8 for weddings?

