Just hooked up three of these last night using DisplayPort daisy chaining. Out of the boxes two monitors were nearly identical while the third was noticeably a warmer, muddier color. I haven't tried to calibrate them yet because of another issue that surfaced.
A few minutes after getting everything set up the monitors began to intermittently go black for a second; not all at the same time and no pattern. Sometimes once in 15 minutes, and sometimes 3 - 4 times in 15 seconds. Looking at the Dell site this is an issue that has been reported previously. I've been on the phone with their technical support folks for a couple hours - actually on hold while typing this - trying to work through the issue. They've had me removing and moving cables and doing other things with no resolution yet. I did draw the line when they wanted me to take my video card out and re-seat it. We'll see how it goes.
UPDATE: Dell is sending three new monitors to replace the first three. Should arrive in a couple days and will see if that makes any difference.
UPDATE 2: This falls under the heading of "DOH! Why didn't I think of this sooner?". The screen blackouts were starting to increase in frequency and I decided to try something else other than just waiting for the new monitors, so I did the only thing that I hadn't done previously, I changed the cord to the second mini DisplayPort output on my graphics card and... yup, you guessed it, there hasn't been a single black screen since.
On the good news side, I'll soon have three new monitors from which to choose one to replace the one that has the odd colors, so hopefully I'll only have to pack one monitor back into a box to return. Also, so far I'm quite happy with the way the two "good" monitors look, and with the thin bezels on these models, it makes for a very nice three monitor wide desktop.