As an aside, does the Nikon D700 have any low light advantage over the 5D Mk II?
Yes, it does. The question is:
does it matter to you? In all likelihood no. Sort of like arguing on a school ground whether your dad's car is faster on a track than your neighbors. Digital cameras are like that, too, it's not easy to find a metric to compare them to.
One attempt is the
Dxomark of these two cameras. As with all synthetic benchmarks, they have to be supplemented by real-world benchmarks.
If you compare the numbers and figures, you will see that the D700 is consistently better. Take the noise chart, for instance. Here, the signal-to-noise ratio is plotted in decibel (as is customary). An increase by 10 decibels corresponds to a 20-fold increase (at first I used the usual convention, but upon research, there is a
different convention when it comes to image sensors). The difference in noise is consistently between about 2.5 and 2.9. This translates to 10^0.125-10^0.145 = 1.33-1.40, i. e. approximately 1 EV. The 5D Mark II has 75 % more pixels allowing the prints to be 32 % larger on either side (1.32 x 1.32 = 1.75). So the increase in noise is comparable to the increase in print size. That's hardly surprising, given the fact that both cameras use state-of-the-art sensors which are limited by the same laws of physics.
So noise-wise, you could say that both are more or less equal. But not only noise increases if the pixel size shrinks, other things such as dynamic range and tonal range are affected. This is something that cannot be compensated for by scaling. Here, the D700 also has an edge. Again, if it is significant, that's a different question.
There are other factors that haven't been taken into consideration at all, e. g. the AF system, how does that work in low light. Arguably, the D700 features a much more modern and sophisticated AF system. (Do you need it?)
Again, I digress that I've used only one synthetic benchmark (for simplicity) to make this argument. You shouldn't compare cameras you won't buy too much anyway, unless you expect some of the technology to trickle down. Nikon and Canon have simply designed the two cameras for different things. I don't doubt that if Canon had attempted to design the 5D Mark II for the same niche as the D700, they would have made a very competitive camera (lower resolution, better AF system).
If I were you, I wouldn't pixel-peep too much and stay away from generalizations such as A has better lenses, B has a better body. In 95 % of the cases they are plain-out wrong. In all likelihood, the camera you use is no longer the limiting factor, today's dslrs are in many things way better than their analog predecessors. 4.5 fps is something `normal' for advanced consumer cameras. A little more than 10 years ago, this was something only pro and semi-pro bodies could do (e. g. the Nikon F100 was capable of 4.5 fps ditto for the Canon EOS3 and EOS1V if you don't use battery grips).
On a side note: I've just had a 3 MP pixel pic (a crop from a 4 MP image) printed on canvas (40x75 cm^2). Turned out great, no complaints in terms of image quality. I've even added noise
You don't need the latest and greatest to take good photographs.
