I just found this out today. I didn't think it would work, but damn if it doesn't kick ass. Emppu finally got to do something besides play barre chords from start to finish, too.
Yeah, they did this on the Once tour and released it on the "Kuolema" single (I believe). I got to hear them do this song in '04 and it wasn't bad at all, considering I am not a Megadeth fan in any way, shape, or form.