Every sensor/lens/filter/lighting combination produces a different range of colors. If you *really* want accurate colors, then you need to calibrate your equipment- otherwise, you can rely on either settings in the JPEG engine, or in your raw converter if you shoot raw. Any two given sensors even in the same camera model will vary a bit, between models a fair bit, and between vendors even more- but a lot depends on what you shoot and how you have your camera set up. For the most accurate colors, you'll have to calibrate and run the correction during import.
X-Rite's Passport works with either vendor's images just fine. Most people find the images made by their camera fine, irrespective for which vendor makes the camera, but *all* sensors from all manufacturers will *not* render all colors correctly by default, no matter if you've got a $45,000 Hasselblad, or a $300 Sony P&S. It also depends on what you're shooting- Asian skin tones render differently than Black skin tones than Caucasian skin tones- let alone flowers, fabrics, etc.- Anyone who says any particular manufacturer's line is any better than another's regardless of settings, lighting and subject is a crack smoking fanboy.
Anyone who says theirs is always right out of the box hasn't ever calibrated and looked at the differences. Are the differences enough to make it worth-while to calibrate? Sometimes for me, other times, I don't need that exactness- or I need the "warming sun" cast instead of a straight white balance...
I've had images published from Nikon cameras without any color correction and with lots of color correction- it all depends on what the client wants, or what I've previsualized, or what I'm shooting. Shoot in Natural, Flash, Sodium and Fluorescent lighting all at the same time, and if you think you'll have a great image without any PP because you picked one vendor over another, I've got a nice orange bridge to sell you.
If you're naive enough to think Nikon would sell a single D3, D3x or D700 to a professional if their colors were that off compared to Canon, or that professionals who shoot Canon never PP their images, then you should probably spend some time actually researching the issue- because lots of sites publish pretty good color range and sensitivity findings, or show examples shooting the same or similar images with a wide range of colors.
No major (or minor for that matter) DSLR manufacturer produces a product today that won't produce usable results out of the camera if it's set up right. By the same token, nobody produces a product today that couldn't use some level of calibration and correction to get more accurate results. That's the nature of the beast- anyone telling you any different is lying or delusional.
Paul
