I recently got hold of a good used D700 at a really good price and decided to compare it with my D7200. According to dxo the D7200 is rated at a good iso 1333 and the D700 at 2303 making the D700 one stop better in low light. But the D7200 is twice the megapixels, has 2 ev more dynamic range and is 7 years newer in technology, so how do they really compare? Here are some sample images at various iso settings, all at f5.6 and the required shutter speed to get the correct exposure. I left both cameras on auto WB to test their performance in that regard as well. They were all processed in NX-D with sharpening at 7 and noise reduction turned off.
These are 100% crops of the images since people generally like to compare at 100% to judge image quality. With no noise reduction the D700 definitely does one stop better but in the one image comparing actual jpeg output of both cameras, when viewed as one would normally view an image, I’d happily shoot a wedding with the D7200. The D7200 also has two card slots and, though 12 megapixels is more than enough, twice as many megapixels which means more detail in good light.