Thanks John, Mike, Tom, Marc, Marcus, Trevor & Doug !!
I've addressed a couple of the points raised by Mike and Marcus with a slightly tweaked image here (the other images are still there at the other links for comparison):
Large:
http://www.pbase.com/image/126802171/original
Small:
http://www.pbase.com/image/126802171/large
I had been quite aggressive in reducing star halos after a nasty beginner's experience with my Eta Carina image. Probably a bit much, so I undid the some of the latter star curve adjustments in the above images. The brighter stars are still a bit harsh; probably the result of earlier star selection layers that were too tight around the stars. I may do a repro at a later stage, but this will do for now I think. Thanks also to Marc (Multiweb) for his tutorial which gave me a few good tips as well.
I also did a final Highlights / Shadows to bring out the fainter nebulosity as per Marcus's suggestion. I'm not sure about it being too blue though Marcus - the colour balance seems reasonable when you look at the star colours (actually many stars are a bit red but that maybe due to the nebula), and it looks pretty
If I do a repro later I may have a play with it ...