Hi Mpsafranski and Jedi!
I have the same or similar issue. I have WT-280s as fronts, a WT-250 LCR, and CT280-IDCs for surround. Sub is a powered Yamaha, stand-alone. I was concerned about the enclosure, or lack thereof, because I used cheap in-wall/in-ceiling speakers in my previous home. But I am very pleased with these Monitor Audio speakers! They rock and sound amazing for movies, games and music, even without midranges in the front, which frankly shocked me. But yeah, if I had the dough for CPs I may have gone that route. Still there's nothing in my current setup that makes me regret leaving the backs open. Anyways. I have been wanting to put 4 up top for Atmos and have had the same question, 2 ways or 3 ways??. I can get 4 matching CT280s on eBay,(2-ways), but should I install four CT280-IDCs instead? And, just because I dont know what I'm missing...should I have gone with IDCs in the fronts?
Let me know how your setup turned out and what you used for Atmos.
Cheers