I just worked on a Samsung UN46B6000 and found the red to be the biggest problem as well. Got DeltaE 1994 all less than 1.5 except for red which was at 7. absolute luminance all within 2. Impossible to get over any further as all the way to 0 and can go no lower. Probably limited by Samsung knowing display cannot replicate any better. If not would be nice if firmware update so it can be moved further.