Fri 18-Jan-13 02:18 AM | edited Fri 18-Jan-13 11:32 AM by ericbowles
Perrone has a great perspective on these cameras for the use that you are planning.
I agree that in fast moving sports it's about timing the 1 frame - not rattling off 5 or more random frames. I do some golf photography and you don't get great images with random luck. Timing is critical.
You'll probably want to use the center sensor with back button AF for the moving horses and rides. AF with the center focus point and a good lens is quite snappy. And tracking is much easier with the back button. When you start moving to the outer points - such as the ones left out on the D600 - you are making a big compromise. Even if you don't use the center sensor for composition, you are likely to be using one of the central group which are all cross type sensors.