fellas, gbeal and rumples, you're both brilliant! Now that settles it
I was thinking about what ponders said about trying to get an inbetween shot of your carina nebula shots. So I tried combining your second shot (the one with the curves and colour adjustments, which I also thinks looks a bit like skyglow) with your 5th shot (the one you posted as being the original, before the levels and curves) in photoshop. I came up with this:
There's slightly more nebulosity but the colour seems a bit washed out. But you're right, we could just go on processing and reprocessing everything but in the end, it's up to the eye of the beholder - if it looks good to you, then keep it. Personally, I like your 5th shot, the original. The balance between the colour and the nebulosity is good. My fiance agrees too, he said he like your image over the processed one I tried, which is fair enough since I agree too! Well, they are all great images so keep it up!