How well the IMPs will do when jogging depends mainly on how the unit is situated. If you let it rest loosely and upright in your pocket with mp3s with a bitrate of at least 192 kbps, you're almost sure to empty the buffer (at least with the IMP-350 as I've personally experienced this) after no more than ~5 minutes. I haven't had the chance to confirm for myself but some say that placing it in a belt pack very much improves skip performance. Of course, the smaller the files, the less likely you are to experience skippage.
