Re: general speaker configuration
The issue with multiple loudspeaker arrays is the phase relationship between their outputs. Not the electrical phase relationship of the wiring but the differences in driver response time. (Fifteen inch cones have a "slower" initial attack than, say, tens.) Any differences between driver response times will create a comb filtering effect between the sound pressure waves that each emits. This appears to "blur" the sound.
Obviously, with a single loudspeaker, this situation cannot arise. Hence, the notion of no blur equating to more cut.