What issues have you seen with the backlight on the ZR24w?
For my specific copy, there is an overabundance of light to the left, especially the lower left corner, and it's a bit too dark at the right. It's visible up to about 5cm into the screen, and pretty much only noticable on even coloured screens or backgrounds, like forums. That's basically it: corner lights aren't equal.
Edit: a picture says more than a thousand words...
Here's a shot in the dark, screen filled with a black image.
Do keep in mind that this is the most extreme you'll ever see, as normally there's environmental light to cancel it out.
Also, I may decrease the brightness soon. It's a bit bright at factory default settings. But I'll just do that when I have to recalibrate. Should reduce this effect somewhat.