Just to cast some additional light on my preference for stereo subs:

Consider an omnidirectional stereo pair of microphones placed in front of a stage at about 15' distance apart (not uncommon). Now imagine a bass drum at the left of the stage hitting a note. That low frequency information will reach the left microphone almost a full wavelength's time before it reaches the right microphone. That bass drum sets up a complex field of phase related peaks/valleys that mix acoustically and vary over time before it reaches your ear. Stereo subs will reproduce this sound-event and it will mix acoustically in your room just like it did in the original recording venue, which will increase the realism. If that same stereo low frequency information were to be summed electronically as it is with a single mono subwoofer, all this spatial information will be lost.

That is my main arugment for stereo subs.

At least in my case, I can tell the direction of low bass by sensing "pressure" from the direction of origin. It is not so much "hearing" the bass direction as much as
"feeling" the bass direction.