I recently posted this pic, and one of the comments alluded to background noise, which I concede is visible. However I didn't find the intensity intrusive, and I do acknowledge that noise perception is very subjective.
I've pretty much turned off most in-camera editing, including setting High ISO NR to "Off', the manual stating that.....This shot was taken at ISO1100 so it escaped any in-camera editing.Noise reduction is performed only at sensitivities of 1600 and higher. The amount of noise reduction is less than the amount performed when Low is selected for High ISO NR.
A fiddle with the image in RAW reveals that any sharpness lost with the NR adjustment seems fairly recoverable with a tweak in Sharpening. I guess I can invest several hours in a series of tests, but I was wondering what other D800 users felt about using the in-camera NR setting.