wow. That is an unbelievable tale.

Jeff, if you don't mind me asking, how big of a "sweet spot" do you get in your setup? Do your multiple subs set up peaks and nulls away from your listening location?

I'm going to guess that it actually isn't too bad, and that careful treatment and room placement helps throughout the entire room... reason I ask is I'm planning (someday) to run something vaguely similar, viz. two "full range" subs co-located with mains and a third "LFE only" in a mode-disrupting position, and wondering how painful the setup might be.

Your experience is encouraging, if amazing!