Thanks for the comments.
Noise reduction is very much a personal choice.
I use this technique.
http://users.westconnect.com.au/~sja...al/colour.html
I find applying noise reduction to the R,G, and B channels in Photoshop instead of the final image helps preserve image detail. Low contrast detail can be affected but backing off the noise reduction for each channel helps.
The trouble with having noise in galaxy images apart from the aesthetic value, it can be easily misinterpreted as stellar resolution.
I prefer to err on the side of a smoother image.
Regards
Steven