My apologies for reviving this old thread, but why not save the files as DNG from within DXO? DNG files are "digital negative" raw files. They may not be Nikon's proprietary NEF format, but the DNG format is preferable to TIFF because it contains your RAW file with all of your associated settings in an open format that is not tied to your camera manufacturer continuing to support their proprietary (NEF) format. The DNG files is also 20% smaller than your original raw file using completely lossless file compression.
I don't understand why this hasn't been discussed or explored.