When I started Raw few years ago, I tested, DPP vs, PS, vs Capture One, and decided that the great interface of PS beat out the others. I did not notice huge differences in quality. But after looking at recent images on my 5D, I called my Canon rep and said, "what the deal on the black (shadows) with this camera, it's a horrow show of poterization. He said try DPP. I tried this clunky software I had not used in years and the blacks looked fine.
I'm really puzzled. I like the interface of CS3 much more, it's integrated with Photoshop and I have no desire to learn DPP, but, I don't know, I'm real confused right now.