But in the midst of this growth, Sirius/XM has lost something which has gone virtually unnoticed:  Portable units. Maybe these things never sold that well in the first place.  I'm talking about the Stiletto 100 and the Stiletto 2.  They were, after all, clunky and poorly designed alternatives to mp3 players – satellite radios with iPod-ish capabilities.  But what these units did that no other Sirius units do is record not just songs but long segments of programming – it's the