The FX's and IDC's are not going to give you what you need from Atmos Speakers.
The FX's a defuser, Di-Poles and Bi-Poles are designed to give you as wide a sound as possible and typically used are sides and rear surrounds. Not what you need for Atmos, where focused sound is the ideal.
The IDC's are a good speaker, but possibly overkill for Atmos use and still not ideal to give truely focued sound.
Others here and on AVS in the US really rate our OSD Black R83a's. They are a 8" speaker but the whole drive is canted 15deg to allow sound to be played towards the main seating position.
We have both 8" (83a) and 6.5" (63a) in stock.
As with any in-ceiling speaker you should strongly consider firehoods as well if you have other rooms above the room.
(Also great for an in-ceiling LCR setup)
Chris.