The D610 is the exact same as the D600 but with a new shutter mechanism that boosts continuous shooting and adds a 'Quiet Continuous' mode. The only other upgrade is an improved auto white balance system. Although the D610 lacks some of the frills, like built-in Wi-Fi, GPS or an articulated LCD, it's a lot of camera for the money. Do the slight updates still make the D610 a compelling option in a growing full-frame market?