Per suggestions of this forum I decided to get the 15'' rMBP. However, for some odd reason it will not output in anything higher than 1080P via Thunderport. If I connect via HDMI it reaches 30 Hz 4K. I have an Thunderport to HDMI converter which then goes HDMI to my TV, which supports 4K and 60 Hz. My television is the LG 40UB8000. Any help would be appreciated.