I have the same 30" Dell panels and I can see the pixels without much issue.
When sitting 2 feet away during normal use?
Of course I can see the pixels when i stick my nose to it.
I know right ... my Thunderbolt display looks phenomenal and when you don't have anything different sitting right beside it to reference it to there's no way you could tell the difference between it and a retina display. -- Not many people know this, but I happen to be quite famous...
I don't know exactly how far but it is fingertip distance and I'm 6' tall, so more than 2' I would guess. I can see the pixel edges of icons and stuff on the Dell pretty easily (like the Premium tags here on DSLR and particularly when italicized). On my T-Bolt display I can't from the same distance. It's odd because the T-Bolt is 109PPI while the Dell is 101. Maybe it is the glass and coating on the T-Bolt that softens the image just enough so I can't see it.