I got this unit
the Starmate Replay ST2 for christmas. It seems to be really well made and has caused no problems for me whatsoever. It does get a bit warm though. The reviews of that XACT portable unit made me decide against it as well as the fact that this unit looks a lot more well designed.
If you get one and activate it before 12/31 you can get the $50 rebate from sirius. I got mine from Best Buy for $79 after rebate but I believe you can get it online for $10 less.
It stores up to 30 songs/artists/teams and searches the channels for what is coming up. If any of those in memory are about to be played on one of the channels you get a warning and can flip to that channel.
It also has 44 minutes of memory so you can pause and rewind live radio.