I loved my Nikon setup but shooting here in Seattle can be rough with the low light venues so I wanted something more capable of handling the dark. My D700's did well but I wanted some more and the D800 wasn't the ideal camera for me (plus the back order is ridiculous). The 5d3's have all the features I was looking for (ISO, dual card slots, faster FPS, good AF) so my hope is that I won't have gear envy for the next 5 years or more. Plus, I'm really loving Canon's 50L. It's a beautiful lens, totally puts the Nikon version to shame.