Thank you for taking the time to reply to my question @inMotionGraphics!
I am rather new to this and after reading on the topic I've realized that your suggestions make much more sense than what I was considering. I have ditched the ATMOS setup altogether as the room is not really built for that kind of sound. (Maybe for an actual theatre room). I think I'd be wasting money on all that gear.
The problem is that I don't have ample space to place two speaker behind the seating area and prefer to put 2 in-ceilings. That is why I wired the ceiling to be able to install two ceiling speakers in the back so I wouldn't sacrifice walking space around the sofa.
I am likely going with the following setup:
2 x RP8000F speakers.
1x RP-600C or 504C centre channel
1x SPL-120 Sub (possibly adding a second in the future so I'm thinking of powering it with a Marantz SR5015 7.2).
I'm stuck on what rear in-ceiling speakers would work with that type of setup for surround sound? Would very much appreciate your suggestion.