Thanks for the input. I've been searching, as others have I suspect, for a DP to HDMI2.0 dongle, but currently I've found nothing...puzzeling. I read hints for availability in Q1-15, but who really knows. Thanks, again.
I'm thinking of using a 55" Samsung 4K curved TV with a GTX780C 6GB and a second 19" touchscreen. Are you ONLY using the tv or are you driving another monitor, too?