I should also add that I would absolutely benefit from some room treatment but to be honest, aesthetics matter more to me. I’m just not interested in hanging clouds or placing random panels on the walls. My goal is to make the stereo sound as good as it can without making my living space look like an audio room.
I have to agree with @elliottbnewcombjr , and with the concept @tomic601 presents, and love that room @tomic601 , but would consider a panel behind your listening chair. I think you will be astonished at the difference. You don't need random panels, but some well placed ones, custom matched to your environment, is going to do more good than anything else. I get it though, aesthetics are part of the enjoyment as well. The problem is change will just be that. Change. Not better, not worse, just different.
Speaker placement if not ideal is going to be a big improvement. Take @elliottbnewcombjr , get an SPL meter, or a microphone. Its hard to guess at proper bass.
I assume you are just using the subs panel for bass management? With the SPL meter or microphone and a way to generate tones, you will be able to dial in more accurately.
If I am understanding your system correctly, the weak link is bass management. I assume your mains are running full range. How loud do you listen? If you like volume, that is going to push the B&W into much higher distortion in the bass. Limiting their low frequency extension and letting the RELs handle all the <80 may be preferable depending on listening volume. DSP for bass management at least for the subs will be a step up too.