lookin good! what happened to cyan in the last chart you posted?
on the low end of the grayscale, the samsungs can be quite touchy. one click of either r, g, or b can send you too far in the direction that you wanted to go. if its being a real pain, and you have to error, its always best to error towards blue. blue is more forgiving than red, and never, ever, error towards green.
do you understand why adding green to magenta helped the saturation?