If I recall correctly, the DPReview.com review of the Nikon D90 said that up to IsO 800 or 1600 it would produce a picture that could not be distinguished from the D300 in any way. The real difference they said, was in other aspects of the cameras ergonomics and some other feature. But in that main usage range, you buy the D90 and its giving you the same picture. Period.

Regardless of 14 bit, 12 bit or any other spec differnece, that performance is good enough for me, lets put it that way. That camera is on my buy list for sure.