Selling 5D MK III for Nikon D600?

Consider a Pentax K-5! Frankly, for the shots you do, apsc will suit perfectly; and with the K-5 you will have better DR, and less or more equal IQ. And for the money of your 5dmkIII you can buy half a system of Pentax lenses. Just take a look at the K-5 groups on Flickr...
http://www.flickr.com/groups/k5/