Two subwoofers or One?

The usual advantage of using two subwoofers is that you will most likely spread out nodes due to room interaction.

Unsound, I know what you're saying, but for some reason (which I haven't really analysed) the omnidirectional radiation pattern of the ML subs seems to not excite room nodes to the degree that regular front firing subs do (I don't know about down firing ones.)

Nsgarch, I'm not familiar with this particular sub, so I must bow to your experience. It might be worth mentioning that it has been suggested that due to the summing of channels of stereo (i.e. not a dedicated sub woofer channel) signals to mono that it is actually possible to deplete information.

Unsound, What you are referring to did happen when people summed the L and R electrically by using a Y connector at the preamp and then running one IC with a mono amp for the sub. But if you keep the two channels separated electrically and either use a woofer with two voice coils (and a two channel amp) OR mix the channels with a buffered circuit and then use a single amp and voice coil, then that won't happen.

Whether one gains more spatial effects when two separate subs interact in the room has been debated. I suppose if a low frequency signal like cannon fire was clearly located on say the left channel, you would notice it, but anything below 120 Hz isn't very directional and I think the room would tend to soften that effect. It's the mid-bass and midrange that gives directional cues, and those are being handled by the main speakers.

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Nsgarch, I can't argue with the truth. I will say that I while most experts agree that low frequencies aren't very directional, I suspect that on some level we are aware of something askew when those frequencies harmonics appear from where they might not aught to be.