I down loaded one of your photos to check the exif data. It was shot at ISO 640 which is getting into the area where noise from the D300 shows up in enlargements. I see in your profile that your main camera is a D4. It might be that the ISO performance gain with the D4 can improve on the added reach of the D300s. That's something you'll have to determine by experimentation. In any case your only other alternative is to get a good noise reduction program for add on filter for CS5. You can also activate high ISO noise reduction in camera but I don't know how effective it would be at ISO 640.
In any case your photos are quite good and the noise is not that objectionable. I don't think they need a lot of noise reduction.