I agree with You_Too; the Mondo BD seems to have the better balanced color grading.

Here you are my attempt of color regrading the 4K using the Mondo as color reference:

Original Mondo BD

ColourMatch'ed 4K

(full res: http://s17.postimg.org/ugli3ajjh/GBU_4k_Colour_Match_RGB.jpg)

Of course, final quality is not so high due to the fact that I used only screenshots; I'd like to test it with some test footage taken from both 4K and Mondo BDs...

Still thinking all of these color regrading discussion merit its own thread!