Well, it looks like I will have to retract my criticism of Capture One
. I just spent an hour on a single shot from the 5D2 at ISO 3200 in both Capture One Pro 6 (latest) and Adobe Camera Raw (latest). I worked each of them to get the best results I could get and in the end was happier with the Capture One image. This was due to CO's vastly superior color tools and rendition, which granted can probably be matched within Photoshop, but this was purely a RAW processor comparison.
That said, it is a bit perplexing that I would have to use such different settings in CO for a 50D file vs a 5D2 file, but it does deliver the goods so I'm good with it. It was a bit more complex to get the desired result in CO in this case since I had to go to the "levels" RGB-histo-graph-adjustment-thingy
to get the blacks to a point where they dropped the blue noise the way ACR does with it's simple "blacks" slider. But then, the CO tool is way more powerful than a simple slider (and I've used it for all sorts of other things than weakening blacks to drop blue noise).
So glad I spent the hour testing, it turned out to be time well spent and I suppose their user support was right that it was a case of 'user error' (though I still question why it is so different between 50D and 5D2 files).