Who's its target?
I'm struggling to see any real point to this device.
First up -- why does it include MP3 encoding? No-one serious about their music will take their master recording in MP3 format. After all, you would have to uncompress and recompress to do even the simplest of corrections or adjustments. Would anyone who would use this feature find any benefit over using an MP3 player's record function? I'm not convinced.
I don't think this is really for bands, we have the problem of "house mix" vs "record mix". Your average gigging band normally has most of its performance volume coming directly from the guitar and bass amps and the drum kit, with the PA carrying the full volume of the vocals with only some "reinforcement" of the instruments. This means that you cannot record from the house mix -- the balance is biased to the vocals. To run two mixes from the inputs requires two mixing desks, naturally, so why not buy/hire a desk with built-in recording facilities -- multitracking even?
The other option is to take the so-called "room mix" -- just plug in a mic and hear what the audience hears. But the quality on that is generally so poor that, again, you may as well just record directly on your MP3 player.
This device is so close to useful: what musicians need now is a dedicated multitrack recorder. One with the bare minimum of knobs, bells and whistles that just saves the raw data and lets us mix down on a PC with the sort of software most of us use anyway.
There are already plenty of ways of recording two tracks -- we don't need this new one.