I'm not sure i know what you mean regarding Nikon raw files they seem fine to me.
For best low light high iso performance on a aps'c sensor Nikon beats Canon hands down when comparing the figures on dxomark there lab tests all lenses and camera sensors. Even Nikon budget d3100 beats Canons 60d on iso performance.
http://www.dxomark.com/index.php/Cameras/Camera-Sensor-Ratings/%28type%29/usecase_sports