This is video 6 of a 7 part series — El Capistan Sound on Sound looping tips. This video goes over How to Get a Constantly Evolving Loop.
If you turn the Repeats down to just slightly below maximum, older parts of the loop will fade away slowly as you play new material.
Demo by Strymon's marketing guy Ethan Tufts (AKA indie artist State Shirt):
http://stateshirt.com