Funny story to this, as this is the very first feature I learned with X3; and the reason was as soon as I installed it, I had a friend here and said "check this out." I started loop recording a few bars to layer some vocals quick, stopped on the third pass and said "Hmmm... something is up..." Comping mode bit me from the get go, and the reference guide pointed me to the record button first (got lucky, I guess).