Hi , I've been lurking around this forum for some time already, love you guys!
So, I have experience with the Onkyo Atmos speakers on a Denon X4300H (which I returned, but that was because of the Spotify mess, in all other respects it was good) with a 7.1.4 setup.
The key to hearing the sound from "above" was angling the speakers correctly.
Back ones worked out of the box... to my surprise, actually, given they were high above the top of the bookshelf behind my main listening position (fancy way to call a couch!), let's say 1 meter from the ceiling and 1.50 meters from my position, roughly.
The front ones were trickier. I have like 4.50 meters between the front speakers (SVS SCS-01) and the main listening position, so it wasn't enough to just place the Atmos speakers on top of them.
I needed to angle them much more before I reached the sweet spot and could clearly hear the sound from above.
In theory there's a fairly decent tolerance for the reflection angle, in practice I needed to fiddle a bit to find the right one, but didn't take more than an hour or so (tested it with eyes closed and focusing on the perceived direction).
Even so I felt the rear ones were more "up and above" then the front one, but that might have been due to the geometry of the room and higher dispersion given the longer distance.
So my recommendation is to try different angles, focus on a couple (front or rear) until you hear the sound distinctly from above, it's possible!
Given my experience I think buying speakers with integrated Atmos speakers is going to be very problematic, one thing is to angle the small add-on, another one would be a full tower speaker.
I was considering them at first (Klipsch ones) but good I went the cheap way first!
PS I should have a picture of the "technology" behind the angle just to give an idea.. I'll try to dig it out