Well I just spent $ 3900 for the canon MKIII + 24-105 and speedlite 600RT.
After reading rave reviews about the Nikon D600 I sold all my canon gear 7D , 50mm 1.4, 430 ex flash and my 70-300 IS , went ahead and bought the the D600 bundle from costco for about 3300
I loved the image quality , it felt weird in my hands for its small body but I got used to it after a week or so , after 700 shots dust start showing in the pictures at f5.6 so I decided to take it back
( love the costco return policy ) and today I couldn't pass the ADORAMA ebay deal
now the waiting game began
good luck, there both great cameras!