Too high can cause neck strain after a while, but if the screen is hidden in the ceiling, once it's down, you won't see anything else except the movie, so you woudn't know it was in the middles of the room.
Rearanging is probably better, providing you've still a SWMBO with you afterwards.
You could always get the pj first and see what it's like on the wall before you move stuff around. The other half might like the idea of moving furniture after seeing 'the big picture'.
Gary.