i dont own one, and its got nothing to do with the xl.
Arpeggiator patterns can be recorded to a Pattern or Song, or chords can be input that will be arpeggiated on Song/Pattern playback. Real-time fun can be had courtesy of the front-panel control knobs, since one of their options is to change how arpeggios play back. And a nice new touch is that arpeggiations assigned to a Voice, Song or Pattern can be transmitted over MIDI, but not those in a Performance. But note that some of the complex patterns don't work with external sounds, because they won't be programmed in the same way as internal ES Voices.
that was the first link in google, to the exact question u asked!
http://www.soundonsound.com/sos/jan04/a ... otifes.htm