+1 for the Boss RC-20XL
used one last year for about a month non-stop, really great. the bar limitation thing described above is annoying be it never stopped me doing anything i wanted to do, just had to think of a different way to do it. otherwise, you can do just about anything with it, i think it has about 14 or 16 minutes of recording time as well, something like that, and you can store 11 different patches as well, and just switch between them without having to re-record.
having said that, the headrush seems to be really good too, obv highly recommended here. almost bought one myself, as it's also a great delay/tape echo pedal and not just a looper. it is a bit limited as far as recording time goes however, and i never felt it was really as good as a purely a loop pedal as some of the other alternatives. it should be noted as well that while you can record 23 or whatever seconds on it, you can only then overdub if you record less than half of that (11-ish seconds), or something like that. it is however, a bit more flexible than the boss in some ways.