I have trying out Capture One 4 and generally there does not appear to be a lot of difference in the output as compared with other RAW processors. One area where there is a clearly observed difference is in the reds as depicted in this shot of a rose. Capture One 4 results in a true velvet look and brings out the fine details of the petals. Nikon NX is my best processor for floral scenes and I was surprised that Capture One 4 is even better.
Note: All settings were essentially defaults except where the exposure was reduced a tad to prevent blown out highlights