Just to chime in a chronicle my pain.
I finally decided to pull the trigger on the 4K Sony Bravia 55X9005B. Been saving up for over 18 months, some obstacles were on the way as well. Finally decided to go and buy it last Friday.
Everything went smooth and the TV was delivered the very next morning (Saturday). Assembled it and started tinkering with my devices. Very soon I started noticing some vertical lines near the middle of the TV. Played FC4 on PS4 and there was a line cutting the skybox in half all the time. Tried the 3D blu-ray of Pacific Rim and there was a beam of light coming from the bottom of the screen all the time. Depending on the scene light, the beam would be shorter or longer.
I grew increasingly worried about this. Finally I started poking around all the menus and realized that there were two vertical lines being displayed all the time. Depending on the backlight, they'd cover the entirety of the screen or just some section.
Here's a picture of what the problem looked like:
Went to the store on Sunday evening. Described the problem. The store clerk was understanding and said that they'd arrange for transportation to the repairshop. But he said that I would have to repack the TV. Which was a nightmare to do just by myself.
This morning a man came by and picked the box up. When I described the issue to him, he said that I would probably simply receive a new device - since noone is going to repair the 4K panels around here.
So now I am waiting for the store's/repairshop's response.
Will keep you posted. Somewhat sad that this has to be my first foray into the 4K world.