I just finished calibrating a couple of these monitors. I used CalMan and their CalPC Client, and an i1Pro. The monitor's built in Rec.709 color space option is pretty spot on. Blue errors the most, but not too bad. It's just the greyscale that needed work. Make sure if you switch color spaces that the "auto EDID update" is set to "on", otherwise the monitor might get stuck in it's "native gamut".