I used to own all-DefTech setup. Then I sold them all.
Regardless of which speakers you own, I think the best setup will be with Atmos - like 5.1.2 or 5.1.4, etc. The reason is not so much about the actual BluRay movies with Atmos. When you have something like 5.1.2 and the AVR with Atmos/DTSX, you can turn anything (even 2CH sources) into something that sounds like Atmos/DTSX using DTS
NeuralX.
Sometimes I watch contents (like TV shows) that only have 2Ch. NeuralX does an excellent job turning the 2Ch into 5.1.4.
I also listen to 2Ch CD music with NeuralX. They sound better than any SACD/DVD-A I've ever owned (I don't miss them at all).
As for in-ceiling speakers vs. wall speakers that are high up to the ceiling level vs add-on modules placed atop the speakers?
In-ceiling speakers would be best.
Second best would be wall-speakers mounted high up to the ceiling level pointing down.
I would not recommend any modules that try to bounce sound up to the ceiling.