ele7en: Yes putting a light behind the screen is actually optimal for viewing, putting a light behind the screen puts less stress on your eyes and any light can help reduce how visible the lcd clouding/backlight symptoms are(you can get more info about this from the Digital Video Essentials DVD/Blu-ray). You will mostly notice these symptoms in very dark rooms/night time, dark scenes/black backgrounds it is less noticeable with some kind of light.
I'm just going to stick with it, my levels are minor and I have no dead pixels. I don't want the risk of a worse screen and eventually if you just watch it seems to get better after warming up. When I watch movies It seems to reduce during the time. It's just something I've learned to live with as even my pc lcd monitor has some symptoms, as long as its not unbearable and no dead pixels it's fine. I think getting a cloud/mura free, no dead pixels and no backlight bleed set is lucky, so you have more of a chance of getting a worse or same symptom level tv if you exchange it. Though I can't say for sure this may not be the case with the w4000 you could still get a symptom free set on a higher percentage as say other lcd models but in my opinion, for the risk and hassle of exchanging for something that could be worse is not worth it if what you have is not very bad.
It's really up to how much you can tolerate it if you want to exchange or not, I've seen some terrible lcd problems (the pictures I showed before of terrible clouding/backlight) and I think the w4000 is much less to what those levels are that a lot of people experience with lcds. My neighbour came and saw my tv and was very impressed, his lcd suffers from terrible clouding problems so I think what he saw on mine was not even noticeable compared to his as he didn't mention anything about it (and is always complaining about his 3rd LCD that he has already exchanged all of which had either less clouding, more or less backlighting but with dead pixels or vice versa)
If it's very easy for you to exchange and you don't have a problem exchanging it more than once with risk factor then go ahead and try if it really does bother you, it's your money and if you don't feel satisfied then you have the right to keep trying until you get what you want.
Overall I must say the quality of the w4000 is superb and the picture quality is amazing, there's so many positive things about the w4000 that just beats anything negative for me right now in which case this negative occurs in almost all lcds to some extent.
