The low-light and high-ISO behavior of the Nikon D3 is terrific, as I’ve seen over and over with real images. By comparison, the chroma (color) noise of the Canon EOS 1Ds Mark III repeatedly gets my attention (eg by misbehaving badly). But at ISO 200?! Get the Canon EOS 1Ds Mark III at B&H Photo.
You bet—click to see a larger image and actual-pixels crops—the poor quality might be surprising. And this example image isn’t even particularly dark; the R/G/B values are in the 40-50 range, as compared to the 1-5 range with the Nikon D3 church shot (heavily “pushed”) in my June 8 entry. To be clear, Canon’s Highlight Tone Priority was enabled, results might be better with it disabled.
Canon EOS 1Ds Mark III @ ISO 200
(strange color was natural smoke/haze late-day sun)