I guess the key point you're missing here is that there's a lag between the XB1X and soundbar when using Atmos - and its not minor - the Demo's work great but when playing a game the lag is up to a second - personally I've set mine to something else other than AtmosHi all,
I have owned the awesome HW-Q90R for a few weeks now so I thought I would update on its performance and any issues.
First of all the latest firmware resolves the issue where the rears or sub were cutting out. This does NOT happen anymore and it has worked perfectly since the update. If you are having this issue still then either a) you have not updated the rears and sub only the soundbar itself, or b) you have a defective unit.
Onto performance, I have a PS4 Pro and an Xbox One X hooked up via its 2 HDMI ports. The Xbox One X outputs full uncompressed Dolby Atmos when watching 4K UHD disks and it sounds incredible. If you want to test out some amazing sound try the following movies:
* Ready Player One
* Alita Battle Angel
* Avengers Infinity War
Also the Dolby Access app on the Xbox store has some impressive demo's.
Certain games also support Atmos including Gears of War 4 and Resident Evil 2. In fairness though, everything sounds really good, even standard 5.1 and 7.1.
Games also fair really well overall on both Xbox One X and PS4 Pro, powerful and incredibly clear. Much better than my old 5.1 setup with Yamaha amp and Canton speakers/sub, with much less cables which is awesome.
Finally I have an Apple TV 4K directly connected to the TV (LG C8) which passes the sound via arc (not eARC) to the sound bar. Within apps such as Netflix it CAN output Dolby Atmos via ARC (but with compression, that I honestly can't hear). Two things worth mentioning here 1) The Netflix app does not state 'Dolby Atmos' for titles I know are, and instead shows the '5.1' badge on the summary screen (where it also shows the badge for 'Dolby Vision' etc). However, upon playing the movie the soundbar scrolls the Dolby Atmos logo. 2) You need to have the sound settings set correctly on your TV for it to pass through Dolby Atmos to the soundbar, I think in the case of the C8, setting Dolby Digital + was the key setting.
Note: As part of this upgrade I have also replaced all of my HDMI cables with Belkin Ultra High Speed cables (48Gbps), which believe it or not actually make a noticeable difference. The Apple TV 4K in particular has known issues with any other lesser cables including blanking and sparkles. A quick search online and you will see what I am referring to. The other noticeable difference comes when switching inputs on the soundbar which happen much quicker with these cables. I am sure many of you in the past have switched inputs and witnessed a black screen or 'no signal' and wondered if it was going to actually switch. Anyway that's also gone with these cables, and they are also future proofed for 8K and HDMI 2.1 devices.
So to summarise, I have had a very good time with this setup, lets hope Samsung doesn't mess anything up with future firmware updates as it seems to be running perfectly now. Any questions just ask, but if you are on the fence about buying this setup my advice would be to go for it and enjoy yourself.
Edit: There is one remaining issue I forgot to mention that only happens occasionally. When using the PS4 Pro or Xbox One X (which are plugged into HDMI1 and HDMI2 respectively) sometimes the input automatically changes itself to Arc mid game and I have to manually reselect the HDMI input with the remote. Not sure of the cause yet.