Haven't got access to a calibrator, so I can't do that. Best I can do is calibrate it by eye compared with my PA248Q.
Out of the box I felt like it needed a bit of work, but as I have a pre-calibrated monitor right next to it, I found it to not be too arduous of a task. Even despite this, the fact that I'm looking to go back for another speaks volumes about it's quality. I know you're interested in the PB278Q, but quite honestly I don't think it's worth the extra hundred dollars PCCG is asking for it.
EDIT: Eyestrain: There is a marked difference in my two monitors in this department, with the BenQ coming out on top. It has the flicker-free thing, which in itself reduces eyestrain significantly, but on top of that it also has the low blue light mode, which initiates a f.lux or gunnar glasses type effect to further reduce eyestrain. I put my GW2765 onto the "multimedia - 30%" mode at night, which I feel is the best compromise between colours and eyestrain reduction.