Last year we got a Sony X930D, 65". It was a bit pricey but at the time still 2/3 the price of similar Oled. We started with the lower end Sony and the light bleed (I'm guessing that's being referred to as dirty screen?) was unmanageable. The upgrade to the 930D was great for 2D but it moved us to active 3D which absolutely sucks compared to the passive 3D on the lower end TV. Since I'm the only person in my house who likes 3D, I took the hit. Having said that, the general overall performance of the TV is astounding. Netflix and Amazon streaming in 4K HDR is basically the pinnacle of television viewing. And, even though standard broadcasts are only in HD, this thing upscales and smooths out all motion so well that the picture looks 4K unless you're dealing with a really low grade SD signal, pretty much everything looks great. This is one significant advantage to not buying a bottom end panel. Sure, it's 4K, but without all the high end processing you really don't get the maximum benefit. Of course, every year the hardware improves so I imaging the processing on lower end units will be improving steadily. My understanding is that oled, like plasma, creates its own light, so no backlight. With the super thin panels and task of processing backlight so that its brightness coincides with the image, you sometimes get light bleed. My Sony X930D has nearly 0 light bleed but we paid extra for that. I'm guessing that those issues will be corrected over the next year or two but buying a 2015 or 2016 model may expose you to that problem. I am very happy with the new 4K experience, but only because we could afford to do it right. As good as it is, there is still a risk of getting let down by a low end 4K tv so shop carefully. If you can go oled, you probably can't go wrong. Also they have passive 3D (when they have 3D) and passive 3D on a 4K tv is the ultimate 3D experience. Full resolution for each eye and no flicker or battery issues. For 3D I still prefer my old 49" LG with passive (despite the resolution hit) over the active on my $3000 Sony. Shame, but overall, the Sony is amazing and 99% of the time 3D is no issue in my house. The LG is in my cave now so I just excuse myself for 3D viewing.