I have the Sony SS-CSE speakers sitting right on top of the Sony Core towers. Flat ceiling with no to minor popcorn.
I cant bring spectral numbers to the table. I can only tell my my anecdote.
They work, not as good as true in ceiling speakers, but a minor effect is felt.
For the most part, to me it feels like there is a bubble of ambient around where the front and atmos speakers are. Most of the sound Ive heard coming from them is ambience.
For example, The car scene from The Matrix, the sound coming from them is mostly the rain hitting the roof of the car.
I watched this series in Netflix called Dragon Prince which apparently
had Atmos track, as the AVR immediately detected it.
I was incorrect. It was Dolby+, but the sound from the rears was being played on the atmos speakers
It did create this awesome ambiance that made me feel like I was playing a video game like World of Warcraft. The movie I was referencing earlier was Fantastic Beasts, which surprised me that it had Atmos sound track on the BluRay version.
I have played some demos which had some specific sounds that were meant to come from above, and there were few instances where it made me look to the ceiling, thinking something was there. It is very rare though.
The speakers are ok. Fit and finish matches the rest of the Sony Core Series speakers that I have; reason why I didnt go for cheaper ones.
If I were to do it again, I wouldn't get them for MSRP. They tend to go for $99 every few months.
Some reviewers indicate that to get better effect, you have to raise the level of the atmos speakers by 5db. Thats how I run them too.
Set up for these speakers indicate they are best when about 1 ft above ear level or 3/4 ceiling height.