Nikon 70-200mm f/4 vs Tamron f/2.8 VC

for it's much lighter

when you carry the lens around all day then the lighter weight makes a big difference

Bokeh on the F4 should be good enough for most cases (as seen in samples)

The lens is light enough the tripod mount is not needed

IQ wise they should be on par with each other

The extra stop can be easily compensated by the sweet ISO range on the D600

AF speed may favor the Nikon since it's proprietary and Nikon didn't provide specs to 3rd party

Cheers