I don't have music in mine as I have a Medtronic but I like choral music too! The first thing I blasted when I got my new speakers was Tallis' Spem in Alium, the Philip Ledger, King's College Chorus version. I got a youtube ripper to get this People's Chorus onto my ipod, although the recording isn't the best, it's also a very nice rendition and I like the spirit of it. One of the "700 valiant punters" blogged about it here which I also found interesting.
That being said, I'd probably go for something a bit louder for my pump/ CGM as I've used some of the choral pieces for ringtones and don't hear them as readily as gunka gunka gunka stuff. Right now I'm using the clocks/ bells from Pink Floyd's "Time" as a ringer which is a nice effect. Then "La Rejouissance" from Royal Fireworks Music for Mrs. and Van Halen's "Eruption" for junior, although I'm not sure she appreciates the significance.