What size x810c do you have?
I'm looking at the 55" and might be getting it this week. I read it's the best bang for you buck basically (if you don't want all the fancy features). I used to have an x850c, but had some problems with it and went through 2 units (I loved the PQ on it though). I told them not to worry about sending a 3rd unit, so I've been without a newer'esque tv for a few months now since I sold my Samsung H7150.
Is there any problems with light bleed, etc, on your set? How are black levels?
I have the 55".
It really is the best bang for the buck, although I've kind of stopped getting hardcore into TV reviews, aside from catching up on the 2016 model Sonys and seeing the changes made. I hear the new Vizio-P series is terrific as well, although I can't say specifically if it's great for gaming.
What size x850c did you have? The 55" was Edge Lit, the 65" was direct backlit. That was actually what made me choose the x810c over the x850c to begin with, as I had a 2012 model LG beforehand that was Edge Lit, and I hated the hot corners. What problems did you have with the x850c?
About the only problem I have with the x810c is the darker corners on some content, but I really don't even notice that unless 3/4 of the screen is a solid color, such as when delving through some Android apps. It's really not present enough on actual content to bother me all that much. I also do get some color shift on the right edge, but again, only when the display is showing some type of solid color background in an app environment.
No traditional light bleed issues to speak of. Black levels are amazing. This is an excellent darker room TV, where you would have a bit more control over the lighting in the room. The set doesn't get that bright, but that's not a problem unless you're putting in a bright living room. It gets bright enough to look crisp and detailed, but the blacks stay inky.
Aside from that, Sony TVs have some of the best 4k upscaling you can find (bodes well for the PS4K). I've not tried a traditional 480p signal, but 720p/1080p look amazing, and 4k content, while sparse at the moment, also looks incredible.
The bottom line with the 55" x810c seems to be that it's an excellent 4K TV in terms of raw picture quality, and comes with a great price tag. But to get such a thing, some sacrifices had to be made. The panel isn't a wider color gamut display (which Sony dubs 'Triluminous'), and while it will read and correctly display an HDR signal, there's no HDR support for actually viewing it. There's no 3D. Also, the build quality is a little subpar. It's very cheap plastic (aside from the stand). It's thick. The bezel creaks about when touched. Mine came out of the box with a couple of screws that needed to be tightened. I heard that the x850c is much better and more solidly built.
Other than those two small issues with the darker corners and the solid color being washed out just along the right edge, I really have no complaints