Sat 23-Mar-13 11:59 AM | edited Sat 23-Mar-13 12:03 PM by walkerr
It's the shadows that benefit the most from 14-bit, primarily if you edit the image to pull additional detail from them. This is the part of the raw file that has the least precision, so the extra bits help the most in this tonal zone. Coincidentally, this is also one of the D800's strengths, so if you really want to harness its full power in terms of dynamic range, 14-bit is the way to go. If not, you're fine with 12-bit. Personally, I have my D800e and D800 set to 14-bit and never change it.
A jpeg resulting from the editing of a 14-bit raw file that's had its shadows lifted substantially will look better and have less posterization than a jpeg resulting from a 12-bit raw file that's been edited in the same manner. TIFFs would be the same way. The key is the raw editing step - not the final format.