Most of the looping examples I've seen/heard are essentially a single progression or groove looped and added to, rather than having verse/chorus/bridge sections and switching between them. From what I understand, that requires a unit capable of multiple loops that can be synced and the most popular ones capable of that are the Looperlative, digital Echoplex and Boss RC-50. Are there any others? At this point, the only one of those three I could possible afford would be the RC-50. Assuming I was building songs based on two or three different loops/phrases, does the switching between the three phrases have to be done manually or can it be programmed?