i have the 3011 and the PA-241
How good are your eyes ? The pixel pitch is about .23 on the NEC 27 and about .25 on the Dell. And the aspect ratio is slightly taller for the Dell (16:10 vs 16:9). If you are working a lot with text this can be an issue.
i haven't had issues with either one.
If i had a second screen, i would use the NEC 27 for image display and the secondary for controls.
i sometimes use the pivot capability of the NEC. The Dell will not.
The backlight compensation and overall evenness seems better than the Dell, but i have no particular issues with the Dell.