If you're going to consider an LCD Display (LED TV) for DARK ROOM viewing, they may present some problems. Currently only plasma has perfect uniformity.

a) Backlight Bleeding near the corners ( Flashlight effect )

2) Clouding ( Due to light guide gap with LCD)

3) Banding Vertical/Horizontal (Issues with LCD Panel/ during manufacturing)

All THESE are according to standard, not defects. 
Samsung ES8000 Banding



Sony HX723 Clouding.

Clouding is less visible with dimming. but they r pricey like some in this forum said u have to b "rich" to get them.

From ur pics ur camera exposer wont b able to capture clouding, overall picture have to b dark, set ur cam to night mode or iso800 or higher.

IIRC your set is a 55HX855 right? This set is 85% of HX955, with lower pirce tag.  I had personally view this, when dynamic dimming is engaged clouding and bleeding is hardly visible to humans eyes. Yes, camera may still can capture them iso400++, but the most important is it can hardly be seen with our human eyes. So to simply put, good dimming solve the clouding and bleeding issues.

I believe the HX855 is using side or left/right  Edge LED, this is evident with its Frame Dimming. The HX955 has edge LED at 4 side with zones dimming.

Again, not all dimming sets are equal, LG led+ is using vertical dimming, as their sets has the led at bottom of the screen,  side ways dimming is not possible, thus slightly lighter black on the 21:9  black bars.

The biggest problem however is those with very good dimming TV falls into the "HIGH END" zones. 

The average non dimming Edge led still suffers.