I know what you mean about film grain. I've seen it in some 1080p BDs before, and it can be distracting. I guess that's what makes it kind of a hot button topic though. It seems like some people feel like if a movie was shot on film then there SHOULD be grain. Others don't like seeing the grain, or at least too much of it. And then that's where DNR comes in, to remove some grain. But then people can't agree on how much DNR to use. Use too little and you may still have film grain. Use too much and you end up making things look fake, like waxy skin, which is the main complaint I hear with T2.
I just watched my first 4K UHD BD, the first Ghostbusters. It actually has a LOT of film grain, and it was super distracting at first. But I noticed two things. After a while, I could mostly unsee it. Except for when I intentionally looked for it again. But also, how noticeable the film grain in changes depending on what's in frame. So for example, the walls in the Sedgewick Hotel and Dana's apartment. They are flat white or light grey, and the grain is super noticeable. To a distracting degree. The rest of the movie though, either my brain did a good job of shutting it off or it just isn't as noticeable.
That said, overall, this has to be the best I've ever seen this movie! Ghostbusters is a pretty good example for me to judge 4K with because it's a movie I've seen a zillion times. So many times on VHS and then DVD, then quite a few times on BD. I was even lucky enough to see it in the theater once. It's hard to say for sure because this 4K viewing was the first time I was really trying to notice things, but I'm sure it wasn't complete BS. There were so many small details that just jumped out to me that I never noticed before.
The pitting in that gargoyle I never noticed before. I mean, I'm sure if I pop in the BD I can make it out. But it never jumped out at me before seeing it in 4K.
This shot in the Sedgewick Hotel really jumped out at me too. Overall, there's so many details in the hotel that I noticed. Like the texture of the walls, stone and tiles. I just never noticed it before. But this shot in particular, the blues in those vases (or whatever they are) really jumped out at me. I just never noticed them there before.
Those screens shots are just pics I took on the TV screen, so they're not exactly a true representation of what you see in person. But even still, those colors pop so much more in HDR then ever before. Reading about HDR, I was afraid it would make colors pop in an unnatural way. Like, they made bright colors pop because the human eye is attracted to colorful and shiny things. The colors DO pop, but in a really natural way.
So yeah, the Sony UBP-X800M2 is a really awesome player. Just taking it out of the box and feeling the weight of it, you can tell it's more well built. I went on for a bit in a previous post about drive noise from BD players. It was a few minutes into the movie when I realized, "Oh yeah, how loud is this player?" It's whisper quiet! I paused the movie and listened for the player, and there's very minimal drive noise from it. I believe this was a BD-100 disc, and I experienced no freezing or skipping, so that's good.
The only negative thing so far with this BD player, and I knew this when purchasing it, is that you have to manually turn Dolby Vision on and off. But the next step up from this player is the Panasonic DP-UB820 which I believe can auto set HDR / Dolby Vision, but it's also double the price of the Sony X800. So annoyingly, I watched through Ghostbusters without Dolby Vision turned on. I did go back and watch a few selected scenes with it turned on, and I think it really is a noticeable difference. So it really comes down to a slight annoyance, I have to check and see if a movie has Dolby Vision or not, and then set that option on the player first before starting the movie. AFAIK though the only way to tell (aside from looking it up online) is to check and see if it says Dolby Vision on the back cover. But it's not large and made to stand out, so it's kind of annoying looking for it. If I don't see it, I'm left wondering if I just can't find it or if it's just not there LOL.
But yeah, overall I'm really happy with this player so far. It seems really well built and it's super quiet compared to the BD drives I'm use to hearing.
edit: I just popped in my Ghostbusters 1080p BD to compare. Overall, just focusing on watching the movie and not intentionally looking for details, I'd say they look very similar. But the 4K just ends up popping more, it looks more three dimensional and less flat, if that makes sense. Mostly I'd say, from a casual inspection, that little things tend to pop more and everything seems a little sharper. Like skin pores and facial hair stumble. Oh, and there's just as much film grain noticeable on the BD as on 4K UHD.
Another edit: Yep, it's definitely a movie watching day for me today. I watched The Thing and it was absolutely gorgeous! I can see this being my benchmark for other 4K movies, if it looks better or worse than The Thing. And I just got done watching Ghostbusters II, which is mostly on par with the first Ghostbusters. Only the film grain is way less noticeable, I think just because there's less opportunity to notice it as much.
I guess I've been thinking about this for a while and this finally pushed me over the edge. 
