What a shame about Apple Support Communities…
I'm writing this in a very dispassionate fashion: for me, what used to be called "Apple Discussions", not called "Apple Support Communities", are most of the time useless when I come up with a non-standard problem, one that would actually take time to think about and answer. This question is the perfect example, a question where no one can hope to rake in ten points in two minutes with a copy-paste answer.
It's hard to believe that there isn't a single one hundred thousand point guru knowing enough about high end displays to chime in. But that's the way things are, and this is one reason why a lot of guys from the old bunch don't bother to come here anymore.
The times they are a-changin… not for the best.
Don't Buy Dell!
I solved my problem very simply: I cancelled my order. Exit Dell. Dell has no decent Mac support for anything including its monitors. Calibrating a Dell U3014 monitor on a Mac is a mess… if at all possible. Simple advice: Never buy a Dell monitor.
Invest just a bit more money (just a bit, not much) and buy a Mac-friendly high end display. I'm talking here about 27 in or 30 in, in 2560x1440 or 2560x1600 resolution. There are several of them. NEC displays are a good example. The NEC PA272W may seem a bit expensive for a 27 in, but it comes with its own colorimeter, and this brings the price back in line with an equivalent Dell monitor.
Most of all, NEC displays, software comes for Mac, Linux… and Windows. Those are not Mac-unfriendly monitors, contrary to Dell.