Both this sample and the RMA'd one are significantly more washed out and hazy at 120 or 144hz vs 60hz. Bleed also worsens at the higher refresh rate. The effect was minimal on the returned one, as any worsening was not particularly noticeable due to how catastrophically bad the bleed and uniformity were. However, it's very noticeable on this example. 60hz on standard setting with brightness turned down to 30 and everything else default looks really good, whereas 120-144hz I have to lower brightness to 20, then change sharpness, put gamma to max and set a custom colour profile (and still it doesn't look as good as at 60hz). This was not an issue on my XL2410T at all, the only real difference between the two modes was the motion was smoother.