Here is a comparison between PhotoShop CS6 and DXO Pro 7. The difference in processing:
The first photo was processed in DXO prior to PS. DXO made the NEF conversion and applied it's magic. That photo was then processed in PS AUTO for Tone, Contrast, and Color.
View attachment 20826
The second photo was processed completely with PhotoShop. PS made the NEF conversion and applied it's magic. That photo was then processed in PS AUTO for Tone, Contrast, and Color.
View attachment 20827
So, the only difference between the two photos is that the first was pre-processed with DXO. The DXO file is a little bit larger, so who knows what that is.
The results are subjective to your liking. The jury is still out on the usefulness of DXO.