I did some more processing on the image tonight. I was trying to get a better Star Mask. Eventually I gave up up Star Mask process and tried a different approach. It was a mix of mostly Colour Extraction and MultiscaleMedianTransform to create masks. With the right options, I got pretty good Star Masks to "fix" a good number of the gray stars. I iterated 3 times through this process to pick up more stars. With more care and time, I think I could have "fixed" the stars better, however it was an interesting experience.
Anyway, I've uploaded a few more versions to astrobin:
http://astrob.in/197456/B/ - The original with saturation boost
http://astrob.in/197456/C/ - Mask applied and stars whitened
http://astrob.in/197456/D/ - Same as previous, but saturation boosted
Edit: Meant to add I looked at JP Metsavainio's tone mapping technique that Rick mentioned, but didn't progress to trying it out.