I just want to weigh in about my experience with this monitor. I purchased it in September 2014 for use with a 2013 nmp. Other than the well-documented issues with sleep mode and getting it to recognize signal on some power-ups, it served me well in a professional full-time capacity until this past week.
I am now getting flicker, random dropouts to black, and visual "glitches" on-screen. I have swapped out the thunderbolt cable with a brand new one but the problems persist.
I contacted LG but it's out of warranty. Hilariously, the support person told me they have many complaints about flickering with macs. His advice included both switching to HDMI (30 hz, useless for my purposes) or using it with a PC. I currently have no plans to switch my entire business over to PC in order to make an LG monitor that was advertised for use with the new mac pro work properly.
I have found all of these problems disappear if I switch to 30z mode while still connected via Thunderbolt.
Obviously my problems don't mean that these monitors are necessarily bad, but I'm pretty disappointed that an $1100 (at the time) monitor has broken down 16 months into its life. I have owned many IPS monitors prior to this, and this is the first time I have ever had problems with one less than 5 years into its lifespan.