Actually I'm conflicted on this Atmos issue.
On the one hand true Atmos movies, of which there are few, the system does marginally add to the effect. But movies and TV is really about telling a story. I really think this complexity adds little to telling the story and come to that going above 2 or 3 channels adds little either as far as story telling goes.
What I have noticed is how these four ceiling speakers improve the audio effect of music from concert halls and especially ambient cathedral spaces. This did come as a surprise. I should add that up mixing music in the popular domain, that is muti miked and processed to death it makes it worse and is a definite negative reproduced though upmixers.
Now If I had not had speakers and amps at the ready I would not have bothered with this to be honest.
However it turns out that for me it was worth the effort, as my only expense was wire, conduit and some MDF, paint and four grills.
I'm lucky as my ceiling speakers are absolutely ideal, as they are pretty much a perfect acoustic match for all the other speakers. They have never once drawn attention to themselves and unless you switch them off would not realize their benefit. It seems to me that Dolby do have their preferred layout correct. Also Audyssey does seem to set the levels correctly.
And of course all these spaces have ambiance from the front of the space, if not more so then the rear and elsewhere. So if this upmixer gets it close to correct then you have ambiance form 11 distinct points in a small room.
I have no idea how close the tonal match of the speakers has to be, but my instinct tells me that for the way I use 11 channels it needs to be very close, or the odd speakers will draw attention to themselves.
As I have said before those little JW drivers have been my acoustic truth test for years. They are extremely well balanced speakers with no crossover to muck them up.
So my experience may be very different from others. I just can't imagine that these ceiling speakers with tweeters right in front of the cone can come close to the fidelity of my JW modules. However I don't own any, and reliable data on them is pretty much not to be found.