Sadly you were right Lakai
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The monitor arrived and it was obvious as soon as I turned it on. The backlight bleed was very noticeable, even in a well lit room. I have turned the brightness down from 80 to 20 which helped a bit but it's still quite bad. I spent a couple of hours on it last night trying to convince myself that I could live with it but I don't think I can.
It looks even worse in a darkened room (obviously). I'm gutted because the contrast ratio is loads better than my old DGM. Dark scenes are much improved (in the areas where there is no backlight bleed).
The question is, do I try swapping it for another one and hope I get lucky or do I spend the extra and go for a Samsung?
Well, firstly I'm sorry to hear about your monitor but if you do have the money for a Samsung, and can live without an audio out jack & USB 3.0...then go for the Samsung.
The Samsung I received has extremely minimal backlight bleed, cannot notice it unless you press your face against the monitor and look down. I might have been lucky, but it's pretty spot on. You'd expect it to be at the 600+ price range.
Also to keep your mind at ease, Samsung promise at least 90% uniformity level for the backlight, which is decent.
I've been using my Samsung 1 week now for Movies, TV, Browsing and Gaming on the PS4 (Need for Speed Rivals = Fast paced game) and it's pretty gob-smacking.
I was never too sure about getting a replacement for my iiyama because if that particular monitor is bad, then the whole batch could be bad this leads to time and effort wasted returning it only to get another one that's the same and repeating again. #nightmare
P.S.
I went for the Glossy/Reflective version of the Samsung - Reason being it provides a deeper, inky black, almost feels painted on type colour which you cannot achieve with Matte finished screens with serious contrast saturation. BUT it's worth noting that I cant really notice the reflection because I use my PC in a very dim lit room...If you used this monitor in an office, it would basically be a mirror.
I hope you find the right monitor soon, and that this message is not too late in your decision making! Do not settle for backlight bleeding, it's not supposed to be noticeable when you spend serious amount of money.