"If you create a linear array very little energy disperses off the top and bottom or in this case to the side walls minimizing that interaction."
The array you described only tries to provide significant smoothing in one dimension, and it primarily does so at one end of the room (your four subs only approximate a line . The same number of subs arrayed differently can result in significant smoothing in two or even three dimensions (if you elevate one of the subs so that it’s closer to the ceiling than to the floor), and this smoothing will extend throughout the room.
"The only thing that really works here is just get rid of the back wall. I am fortunate in that I designed my media room without a back wall."
Relatively few people have that option. I have a hard enough time selling four subs without also requiring customers to remove their back wall! In other words, regardless of how well what you are doing works for you, it is not a generally-applicable solution.
"I am not sure if spreading other sub woofers around the room would minimize this or just create more complex patterns."
More complex patterns of modal behavior is how modal smoothing naturally occurs in a large room. The reason a large room has smoother (faster, better, more natural-sounding) bass than a small room is that the larger dimensions result in greater de-correlation of the in-room bass energy. Greater decorrelation = smaller and more numerous peaks and dips. A distributed multisub system mimics large-room modal behavior in a small room.
Duke
