Both devices will store their recordings in a separate folder called "Recordings" on the top level of the iPod. You can choose between "high" and "low" quality for recording. "High" is 16-bit/44kHz WAV; I have no idea what "low" is, sorry.
WAVs can be converted to whatever format you wish in iTunes, using the "Advanced" --> "Convert selection to <whatever input format is set in the Advanced preferences of iTunes>…"
We just briefly tested these devices in the store; unfortunately, I cannot attest to battery life at all. Both worked well enough, though the Belkin seemed a little more solid to me. The MicroMemo wasn't recognized at least once until we reconnected it, though that may have been the Dock connector on the demo iPod.