I have a similar arrangement with two couches as you do. The left front looks funky, but everything sounds just fine. The tweeters are above the arm rest, so I suspect it doesn’t degrade SQ at all. I moved my 600 all over the room with the corner position as my first choice, but I ended up placing it right where your mid room X is. When the sub is too close to the listening position, I can identify where it is by sound….which is a bad thing. Moving it to the mid wall evened out LFE throughout the room.