I plan on replacing a 5K iMac and using 2x 5K LG + tbMBP...anyone else using the MacBook Pro as a desktop workstation? i.e.; 5KLG + MBP in clamshell? or at least for extensive periods of time? I'm curious if anyone has experienced burn-in from the keyboard onto the screen while using the MacBook in clamshell mode? I knew this was a problem on some of the earlier unibody MacBook Pros I used, but have not used the rMBP's in this configuration exclusively.