I swapped out my QS8s for M3 on-walls with anticipation of Atmos and DTS:X and really like them.
My plans for ceiling speakers are to get unfinished M3 onwalls, painting them to match my ceiling, and making a custom "mount" that puts them at a slight angle towards the listening area. The angle is mainly because of my ceiling being less than 8 feet tall, so my plan it to try them a little further away to compensate for the lacking height, and then angle them to compensate for them being further away.
Someone else here has the M3 in-ceiling speakers and wishes that the tweeter was aimable.
Hopefully that helps a little.
