Nikon D600 vs. Canon 6D in Low Light?

DPReview007 wrote:

Which one is better in low light please? Yes, I can go on DxO Mark and see that the Nikon is rated higher. Yes, I can go to the Conclusion page of the each review here on dpreview, and see that dpreview also thinks the Nikon is better a bit.

The problem is, when I go look at most other reviews and the sample images there. People say the 6D is maybe two full stops (!) better when you crank the ISO up above 3,200.

Could somebody please explain the discrepancy?

I bought the D600 plus the Nikkor 24-70 f2.8 lens. Now, after about 4,000 shots, I have all the smudges on the sensor. Considering returning it and buying the 6D instead (and keeping it until the 5D Mark IV comes out in a couple years) with the Canon 24-70 f2.8 Mark II (which is said to be superbly sharp across all focal lengths.)

Thank you!