I went through 2 of those NEC models you are talking about and I found the Sony G520P to be better overall. In my experience the NECs I had both had flaws and text clarity problems that simply would not go away. The first NEC I tried had problems with geometry that could not be adjusted away. The second had text fuzziness that I could not clear up.
The Sony I have now is great for what I want, mainly text clarity. It also has fantastic geometry and color purity.
I know why you're considering the NECs and it is true they have better specs in some ways, but I had big problems with mine. Luckily I ordered from Dell, when they were paying for return shipping on those beasts so they picked up the bill for return shipping for me. I understand now that they are making the customer cover return shipping now, which is bad on the big 21" monitors. I paid $80 to send a big dog cross country via UPS ground. Something to think about.