I have a U2713H sitting here next to my Thunderbolt display doing nothing right now. You might want to take a look at http://embdev.net/topic/284710
if you go with it, the U2713H has a wider gamut, and colours can look over saturated at times. Too much so for my line of work so I use the Thunderbolt display (perfect btw) solely now. But when my Mac Pro turns up, I'll be hooking the U2713H up as a second display. Just thought I'd point that out to you.