"Intuitively, I'm thinking the array format is designed for SPECIFIC pro sound applications, and will create more problems than it will solve if implemented poorly. I'm not clear what characteristics it has that would be so desireable for home use that acceptance of the self-interference and parallax issues would be considered worthwhile." I strongly second that idea. BTW, Sam, I have JBL cabinets with 4 15's operating over the same range; JBL wants them crossed over to the mid at 297hz. "The Diamond Quad array orientation allows the four drivers to create maximum output, while minimizing destructive interference effects caused by the use of multiple drivers operating in the same bandpass region".
BTW, efficiency for these beasts is 103db.....! Max SPL 143db MBB