Bad version depends on your POV. Many pros like the LG color, clarity, and uniformity better and are disappointed when they get a Samsung. A few LG SA1s suffered from IR, which will get repaired under warranty. You can try to color calibrate to adjust colors closer.
My BTO ordered directly from apple and shipped from China a couple months ago is an LG SA2. Dunno what they are shipping now, probably whatever they have on hand.
I have a 2012 BTO 15" that I got on 4 December 2012 and it has an LG SA1 screen. I've been using it every day since and no sign of IR or any other defects to report. It's been a fantastic screen and computer.