Aglet, how about you provide us a beautiful RAW file that you spend time, effort, and possibly money to get first? Please do show us the very best d800 RAW file of you very best work and then I promise I will do the same.
It must be your best, no less.
how about something easier, you show us some 100 iso test shots from your 5d2.... if you still have it.
Blank sheet of white paper, exposed at 1 EV values from +4 to -10, no Lum or Chroma NR, black level crusher set to ZERO, pushed in ACR or LR, until visible banding appears at 100%
Show us what EV levels you no longer get FPN.
Do and post that, then I'll do the same with a $400 Nikon.
OK, you go'head and do yours. We're waiting.