For the most part, my view on DxO is similar to how i take DPR and the rest of the "in-depth" review sites... with a grain of salt. Getting a top of the line camera isn't going to make you a better photographer... It CAN however give you a higher ceiling to learn... It CAN give you more options and make things easier, faster, cleaner, but it will vary from photographer to photographer. Nikon, in theory, has typically scored higher than canon in the last half decade in these sort of tests, however a good chunk of National Geo's staff and field photographers shoot canon and get great images.
As far as DR and such, as another has posted, in post, it gives more flexibility and room for editing... while that's fine and good, your forgetting a lot of "pro" photographers, when it comes to photoshop or post production, are lazy. You would be surprised how many pro's outsource photoshop work. You would also be surprised how many dont outsource but "shoot to print"... They use an expodisc or the like, nail WB, nail exposure, shoot, and then do little in post to prep the files... If all of a sudden the files are turning up flat, that isn't going to sit well as it defeats their business motto. Of course there are some "low volume" photographers who charge more per shoot, they can afford spending time in PS or LR and clean up images all day long, but that is going to get old quick. So there's different angles to look at everything.
Lastly, coming from a background of shooting cameras that weren't the most opportunistic cameras, such as toyo's for LF instead of sinars, bronicas and kowas instead of Mayima and such... I have learned to adapt, to make the best of my equipment, and not to worry so much about numbers/test/reports as if i have, I would have dropped out a long time ago... In the end, it's not the equipment nor what some test says about the equipment, it's about how you use said equipment.