RE: Gaming on this projector: I'm seeing a lot of people here who are kind of bummed about the input lag, but I firmly believe the lag with a 4K signal isn't that bad. Remember, folks like Sage are using a 1080p input lag measurement device (because the 4K version is super expensive). Their measured lag figures should have an asterisk next to the value, because it's really hard to say what this thing's lag is with a 4K signal (which anyone with a PS4 Pro or an Xbox One X will be outputting to the projector).
I am the very definition of a casual gamer, admittedly, but I've been able to game just fine on this thing. I play Doom, Red Dead Redemption 2, GTA 5, Assassin's Creed Odyssey, and many other games just fine on it. I don't see any noticeable delay between when I push a button on the controller and my character does the thing associated with said button.
"Okay", you say, "but obviously there's SOME amount of input lag. You might not be noticing it, but it might be hurting your performance". Fair enough, but I also play Overwatch, which is an esports game that is highly affected by input lag. I also play Ashe, who is a character ESPECIALLY affected by input lag, because she needs good aim or she's useless. I have played plenty of Overwatch on both the TK800 and the TK850, and before that I played it on an HT2050 (not the A revision). The nice thing about Overwatch is that it quantifies your performance with a Skill Ranking, if your ranking goes down, you are playing worse. My skill ranking in Overwatch has always hovered between 2000 and 2500 between all three projectors. If the TK850's lag was really appreciably worse than the TK800 or HT2050, I'd have seen my Skill Ranking decline over the past few months playing with the TK850. My skill ranking hasn't declined, I don't feel like I'm missing shots more often, and overall the responsiveness "feels" the same between the three projectors.
So, all in all, it probably comes down to skill level. If I were a way better Overwatch player and had a 4000 skill rank, maybe the input lag would be problematic. But for an average player, the TK850 is fine for gaming (IMO), even on esports titles.