I'm using a Nikon D300 and shooting raw. The defaults for long exposure NR and high ISO NR were set to OFF by default. Except for shooting delays, is there a quality advantage to doing in camera NR prior to post processing or should these settings be left OFF if planning to do post processing?

My apologies if this was answered previously, but the search turned up too many posts that didn't answer the question.

Sorry for my canon-oriented answer - I don't know the D300 but here are my 2c's anyway...

These 2 things may not be the same : if "long exposure NR" means the camera taking a black frame of same duration and substract it if from the picture, it deals with mainly dead and hot pixels, and may be seen as hardware-related NR - something that's hard to do in PP.
Do it if you can afford it time- and battery-wise (and if I'm not mistaken in what it is ;o).

Otoh, I understand "high ISO NR" as a more conventional NR, more or less averaging adjacent values.
This may be better made in a powerful computer than in your camera.

The in-camera noise reduction does not affect the raw data with the D300. Actually, the only camera I know of, which carries out noise reduction on the raw data is the Sony A700.

Which means that if you want to shoot RAW you have to go hunting hot pixels in PP instead of just using dark-exposure NR to get rid of them?

...


Kind of inconvenient.

My understanding is that dark or long-exposure NR *is* applied to RAW, but not high ISO, which is only applied to jpeg's in post.

In-camera for long exposures.
Software/post processing for everything else. Capture as much detail as you can, and deal with noise (mostly color noise, luminance noise doesn't bother me much, as it's just mostly "grain") in post.