I have NR set to NORM on my D300 & undertake any (additional) noise reduction as part of a post processing step. Although I prefer to have more control of the final output, not just NR, I will still be interested to see the comments of other users.
Fully agree with Wayne Would se to normal Remember Noise Reduction will affect sharpness Best to control how much and where.
The D300 performs well and has low noise, I'm comfortable up to 800 and will go to 1250 under good light conditions. At higher ISO you will be using noise reduction software ( I use NoiseNinja) but can produce a good image.