I've seen them, but I haven't done a side by side between a quatron and a non-quatron display. I think that this is the hard part... getting two nearly identical displays side by side. Likewise, I think that they do some other upgrades to their quatron series to make them look better than the non-quatron models.
I have installed a 60" and 2 70" quatron displays and was not overly impressed with them. I think the Samsung displays still look far better for LCD.
