Thanks. Well, to reiterate,I do not want to be tied down to a metronome or a clock, but need to be able to sync multiple loops together. So I need a "Master" loop, and "Slave" loop(s). For example, it the Master is one measure long, a Slave loop could be one measure long, or any multiple of one measure, depending on when you stop recording and "close" the Slave loop. If you then start the Slave loop later, it will always be synched up with the Master. This is the way my hardware loopers (Boss, Boomerang III, etc) work.
But with Loopback, things are OK until I try to get two (or more) instances of Loopback to synch up and behave. It seems there is no concept of "master" and "slave" looping with Loopback, and that I can only "slave" loops to the Concert Tempo. Well .... If I set up my first instance of Loopback to "Set Concert Tempo to First Take" then the timing of the loop gets sloppy, especially if am trying to do precise looping. When this approach is used, I can get subsequent instances of LoopBack to synch to the first loop, but the inaccuracies of timing the first loop make this method unusable for accurate timing (at least the way I have it set up!)
There are ways to "Group" Loopback instances, and I have also played around with this quite a bit, but this just seems to set the loop lengths the same for all loops in the Group, and they respond simultaneously to footswitch commands, and it doesn't seem to be useful for live looping if you want your loop lengths to differ in multiples of the Master loop length.
CCT, I certainly could be missing something; there are many parameter variations that could be selected in each Loopback instance (where the first is the "master" and the second is the "slave" loop). I have tried too many of them to remember or list, but I thought I tried all of the logical ones after reading through the docs and experimenting. If you know of some things to try with specific parameter settings, I will certainly put some more time in on it, cause I would love to have it working for live performance!