It seems like turning the backlight to 0, as you described, creates a second problem. Let's address the first problem that causes you to want to reduce the backlight, which is the screen uniformity.
You may set up a service ticket and have a service technician come out and diagnose the initial problem (if you can reproduce it in his presence, I've found that helps!). You can call 800-SAMSUNG and have a tech scheduled to come out, if you'd like. Ideally, if we're able to fix this issue, then you won't have to drop your backlight levels.
Keep me posted.
I purchased this LCD TV about 6 weeks ago. In darker scenes, the backlighting on the left side of the screen is very uneven using default settings. There is a band 5 - 6 inches wide, which extends from the top to the bottom of the screen, which is much lighter than the rest of the image in dark scenes. This can be tweaked by reducing backlighting to zero & increasing overall brightness to compensate. However, the lighter 'band' cannot be eliminated this way and the aforementioned tweaking degrades overall image quality. 2nd issue is: when you reduce backlighting to zero, the IR for the satellite dish stops working. Samsung tech support has not been able to resolve this. Does anyone have any suggestions?