4k refresh rate MacBook Pro 15"

Hey! How are other users with mid 2015 MBPs getting on with UHD @ 60Hz getting on out there? I get the feeling this UHD stuff isn't really as matured as vendors would like us to believe...

For about a year I was able to run my external display at 4096 x 2150 and 60 Hz, suddenly the monitor started playing up (flickering). Thinking it's obviously the monitor playing up it's actually been back for repair twice now, still no change. Oddly my MBP that I use for work doesn't have these problems, but cannot output the full resolution of the monitor as it doesn't have the discrete GPU. So I pushed my Apple vendor to check my MBP hardware, they can't find a fault. It's covered by Apple Care so we pushed for replacing some of the components which hasn't done anything either.

When returned from service I couldn't output anything above 3840 x 2150 @ 30 Hz until I changed the plug on the MBP power supply to the corded (earthed) version. Now it will briefly display 4096 x 2150 @ 60 Hz before starting flicker again. NVRAM has been resetted many a time, I've switched output ports, I've tried DP-mDP, mDP-mDP connectors, my last resort was a €30,- cable, all to no avail.

The current bottom line for me is

- UHD is picky and requires top-grade, shortest possible connectors

- 60 Hz, the full resolution of my monitor and Displayport 1.2 are not a reliable combination.

At the moment I have resorted to running 3840 x 2150 @ 30 Hz with black bars on sides. I don't neccessarily need the 60 Hz refresh-rate as I don't watch video or game but I do get the (subjective) feeling of tiring sooner. Considering the cash I put into the hardware I was expecting better things.

What have your experiences been?