From wharfratjoe, who reached out to Zoom's customer service department:
Zoom support clarified it is a mono file even if you use stereo mics. It will only record the left channel.
So...a stereo input that only records to mono. Lame. Super lame.
It's basically just a less expensive Tentacle TRACK-E, which also isn't built for our purposes. And obviously a deal breaker.