I have the D800 and have returned my 5D MK III after a month (I bought a 1D MK IV).
The DPR review is pretty accurate based on my experience. Each camera takes excellent images, and has its strong points as well as weak ones. I'd grade them as being equal myself, but one camera might be better at certain things. One thing for sure, computer makers and SSD makers will benefit from owners frustrated with the time to process the huge files. I like the D800's extra features like the built-in AF-Assist light, but the menu system is horrible. It seems like there is a button for everything, but trying to find them in the dark is bad news. The other bad thing about the D800, and DPR mentioned it, perhaps not strongly enough, and that is the need to use the very best glass, and the utmost care in setting up your shot. Otherwise, your images will be no sharper than the 5D MK III. It makes good lenses look bad, so plan to buy only the top lenses and spend $$$$$!
I may very well sell the D800 and get another 5D MK II to go with my 1D MK IV.
Are you enjoying the 1D4 then?
Yes, its a great camera, the best I've owned for my usage. Obviously, MF was better for portraits, and the D800 is also excellent, but you must be deliberate and careful, and use the best of the best glass. I can definitely see the better resolution in D800 images, but I rarely need that level. I did need to crop severely at a recent event, where the only Nikkon lens I thought was usable was my 24-70mm f/2.8G, and it wasn't long enough. The cropping ability can be useful.
Here is a 1D MK IV image at ISO 12800
And one at 12800 with the D800. Both require a lot of NR, but will print fine at reasonable sizes.