Humayun, I really enjoy this image. Well done. I spent a good 20 minutes studying it. The processing displays subtle details and the core (Hourglass nebula) isn't burnt out, not easy to achieve when the object has such a large dynamic range. However, I feel you could have exploited the dynamic range a little better. The nebula appears to take on a mono tone appearance throughout the object. The Hourglass nebulosity to the upper left of the open star cluster NGC 6530 is typically much brighter. This will then display the dark dust details and provide the image with more dimension. I feel your star colour balance is looking good, but do agree with the others that the image looks warm. Looking at the image in PS, the red histogram data is quite strong. You could perhaps drop this with curves on that channel only - then boost it back using colour balance. The image warmth doesn't appear to be coming from the nebula itself, but the background star clouds. So if you don't want to change the nebula tones (which I think are good), you could simply use the colour range tool to select the background only, then drop the red curve. Doesn't need much that’s for sure.
A quick tip that I use to determine how the background colours flow is in PS, use the image | adjustments | equalize tool. It will show you which colours dominate the background and assist in determining gradients. If you shoot from sky polluted areas, this is a helpful in detecting green/yellow shifts. The tool works best for wide field shots, so if you're going to use it, do so before you crop your object of interest. The narrower the field the more analysis is required to determine the background colour shifts.
Keep up the good work and look forward to seeing more from you
