Hi Joearch,
There's certainly merit in using two subwoofers to improve and even out low-bass coverage in a large and problematic space. But as to the "rumored" stereo effect: You DO NOT lose stereo cues for low bass by using a single subwoofer fed by the LFE signal from your processor.
What no-one understands is that the directional cues for bass frequencies are supplied by the initial transient sounds that are much higher in frequency and are preserved by the left/right mains and surrounds.
For example, when a jazz bassist plucks the the string, or a percussionist hits a tympani, the "pluck" sound and the mallet hitting the drum skin is the transient that gives the deep bass energy its directional component. And those sounds are almost all in the midrange. So don't be concerned about "losing" directionality with deep bass by using a mono subwoofer feed.
And crossovers don't "cut off" as if sounds of a certain frequency fall off a cliff. They gradually lessen in intensity, determined by the slope of the crossover. The two slopes overlap each other.
Regards,
