Cool. Like to see specs.. along with response graphs and polars of Mid/Side pattern response. The reported ability to control multiple units and sync clocks with the app is intriguing, as long as sufficiently close sync is able be maintained between units. Unfortunately 4 hours of battery life is very short.
The tininess of MEMS elements usually translates to a high noise-floor. I imagine the four MEMS mic elements of the primary Mid channel are run in parallel to achieve better noise performance. Not sure what that means for Side channel performance, as the two MEMS wired in reverse polarity to produce the fig-8 Side pattern will only provide for the equivalent noise performance of a single MEMS element.
May pick one up to play around with.. in addition to easy low-profile recording I'm thinking it may prove useful as a spot mic, say for vocals or quieter instruments when recording on-stage without SBD access.
Conceptually, this is getting close to my long-imagined miniature DPA Mid/Side "puck" which would incorporate a Mid/Side pair, possibly with integrated recorder, in one of the miniature DPA hard rubber boundary mounts. Already wondering about disassembling and repackaging it into something appropriate for my arcane stealth recording methods, which would ultimately incorporate 3 or 4 of these in an array.