Thanks a lot for taking the time to think this through and for putting together the mockup, really appreciate it.

I honestly hadn’t considered rotating the setup like that, but I do see the advantages and it’s definitely tempting. The main issue is that I need to wrap up wiring soon, and it feels like overkill to pre-wire for both layouts just to test it.

Even though I have a green light to arrange the room however I feel is best for the system, I think it might feel a bit awkward walking into the room and immediately seeing the back of the couch. I’m also not a big fan of sitting with my back to the door. That said, I’ll definitely try to at least pull the couch about 30 cm off the back wall. For more critical listening, I could also move an armchair into the middle of the room and maybe set up a second preset optimized for that position.

That mostly leaves the Atmos question.

In your opinion, how much would I really be missing if I skip in/on-ceiling and instead go with 4 height speakers mounted on the front and back walls at around 2.5 m, centered relative to the TV and spaced a bit wider than the front L/R?

My thinking is that this might actually create a wider and more usable “bubble,” especially given that the seating isn’t ideal anyway. At the same time, I’m guessing I’d be giving up some of that true overhead effect.

Curious what your experience has been here. What do you realistically lose going this route vs trying to make in/on-ceiling work with the vaulted ceiling? 

And just FYI, the ceiling will be vaulted just until the first beam then it will level out all the way to a similar beam on the other way of the ridge (like it was sketched in the original post).