The colors look really good. There’s a lot of noise in the sky, though. Is that in the source? If not, I would suggest increasing the stabilization parameter, which should reduce the noise substantially. You might need a few more color spaces to converge to the reference colors, but with the increased speed of v2.1 it should not be a problem.
The MGM Blu-ray is pretty noisy and there’s a fair bit of macroblocking in the sky as well, so I suspect that’s where the problem comes from.
Here’s an untouched screen from the Blu-ray:
http://i.imgur.com/QOhC1C5.jpg
And here’s the same image with the levels pulled way down so you can see the amount of noise in the sky:
http://i.imgur.com/vVuNJaT.jpg
I’ll try creating a new LUT with a higher stabilisation setting and more colour spaces to see if that helps.