I am struggling a little bit to adapt to the lack of the visial focus confirmation on the 5D Mk iii. Okay, it does exist - in the bottom right corner of the viewfinder but it isn;t obvious and requires a very deliberate movement of the eye to look at it. This wasts time and slows things down, IMO.
I pretty much use the centre focus point for 99% of the time. On the Mk i and Mk ii, regardless of the ambient light levels, the focus point always momentarily flashes the instant focus is achieved. Since I shoot wedding I turn the audible focus confirmation off. This little flash of the focus point gives me the confidence to know that focus has been achieved. No more wondering.
But on the Mk iii this only happens in low light. In medium to brighter conditions, unless you waste half to one second to take your eye off your composition and check the tiny focus confirmation icon on the bottom right corner, you do not know that the camera has achieved focus on the subject.
I wish they would make a firmware update to add this to a menu item and make it an optional visual focus confirmation - either as it is (low light only), or to always give the little blip of the focus point.