Thanks for the comments Paul, Allan, Greg and Geoff. It's nice when all the time invested in capturing the subs results in an image you are happy with. It's also great to receive such good advice from the really experienced astrophotographers - thanks!
Thanks Rick. Processing is an interesting exercise - I spend hours staring at the screen and then post an image that I think looks good - look at it the next day (or get some feedback here) and the issues become really evident. It is great to get so much feedback from such a wide group here. I've picked up some great tips about NB and LRGB processing in the last month.