You can always down-res from 36mp to 16mp and achieve the same IQ in low light (handheld or otherwise). But in good light, you will never have the resolution that is possible from the 36mp sensor.
- If you look at photos from the D4 and the D800 taken at ISO 25,600, you will see that all colours, blacks in particular, look cleaner on the images from the D4 also after the D800 has been reduced to 16MP.
- While maximum ISO for a D800 is 25,600, it's 204,800 for the D4 (and Df), 3 stops more.
- A RAW file from the D800 is nearly 60MB while it's around 35MB for the D4. That translates into a need for almost twice the processing and disk capacity to handle the D800 files compared to those from the D4 (and Df).
While there are photographers with a need for 36MP, the vast majority don't have that need. Clean ISO 204,800 files on the other hand, seems to be all the rage now :ROTFL: