If you have a steep-slope lowpass filter (24 dB per octave), then you can get away with spreading subs around the room. Most subs have a 12 dB per octave lowpass filter, and so will give away their presence and not blend well because they allow too much lower midrange energy to pass through. Since the ear localizes by arrival time as well as intensity, it makes sense to me that if the subs are passing audible lower midrange energy you'd either want them close to the mains, or farther away from your listening position than the mains, or both.
Since the low-pass driver is phase-lagging relative to the high-pass driver, I don't see any theoretical disadvantage in the bass region to having some of the subs a bit closer to the listening position than the main speakers - provided the above recommendation regarding crossover slope is observed. That really is a crucial aspect of a scattered multisub setup, in my opinion.
Duke
Since the low-pass driver is phase-lagging relative to the high-pass driver, I don't see any theoretical disadvantage in the bass region to having some of the subs a bit closer to the listening position than the main speakers - provided the above recommendation regarding crossover slope is observed. That really is a crucial aspect of a scattered multisub setup, in my opinion.
Duke