Social Entropy's Engine sequencer has a nice tool called "Snapshots". Snapshots are an entity type (along with Patterns, Chains, Songs etc) on their system that gives a pretty fast way to generate song structures. Simply, you get a loop running with whatever track configuration you like and press "Snapshot". It then saves all the track config, mute states etc in a "Snapshot" object. Tweak away, change some mutes, or track config (channels, FX, etc) and press Snapshot and you get another save poi