I received my first PG279Q today, ordered from Amazon (U.S.) on 1/29 during a serendipitous moment when it came back into stock while I was checking the page (at Amazon itself, not a third party vendor).
The top side of the box had two layers of factory packing tape, but it turned out to be a December '15 model so I'm unsure whether it had time to be pre-owned.
I've spent the last two hours inspecting the panel (haven't tested the overclock or G-Sync). I can't find any problems with uniformity and there are no dead pixels or dust specks, all of which would have been immediate deal-breakers. BLB is present (mostly in the lower right) but it's hardly noticeable above IPS glow, the latter which is at normal levels for a panel of this size. I'd really have to be looking for either effect in a dark scene to see them.
I thought I had won the panel lottery before I noticed what I think are called "pressure marks" along the lower edge. I am less familiar with this defect so I was not looking for it initially. There are 5 small splotches of irregular size (the largest two about a square centimeter each), shape (I'd best describe them as nebula-shaped), and brightness (some areas exceeding 100% white). They don't show up in photos well, so the image below has been edited to exaggerate the effect. These are most noticeable on light colors and while viewing directly on-axis. But now that I know they are there I can notice them starting at about 25% gray (e.g., in my task bar). I read earlier in this thread that some have noticed their defects going away after a bit of acclimating. Will this kind of thing lessen over time? I'm not sure I can get used to this, and I definitely don't think it's acceptable for a product at this price point.