Though I can’t give you any feedback on your looping tools now that you’re a MoBo software guy, I can tell you what I know works.
Things to consider, are you wanting to switch the master/slave sync relationship? Will you be the constant clock source? If it’s the former I suggest getting together before the gig, hooking it up, and seeing if it can work smoothly, which would allow greater performance flexibility, as either person can start the first loop. Tech rehearsals always seem to mean less perspiration come gig time.
If you are acting as the master only, Per’s idea sounds the most logical but would require an additional midi pedal and perhaps a small midi merge box, as well as the time it takes for the script writing. I’ve had good luck looping percussionists, but it takes some practice to get smooth at it if you are trying to achieve precise groove loops. If you have a drum machine, try running it through your looper, un-synced and work on your punch in punch out timing, creating drum loops. The drum machine don’t lie, and it’s a good way to get familiar with what ever latency is inherent in your looping rig, not to mention your rhythmic acuity. If your band mate is new to looping, you might avoid train wrecks by looping him, particularly if you have no time to get together. This does however give you more things to multi task, and if you ask me we could all stand to do a little less multi tasking. Last night as I was leaving Trader Joes with the much needed half in half, I nearly was run over by a guy on roller skates, who was weaving, talking on a cell phone and with the other hand holding a potted plant, and I believe under the influence, hear nearly skated himself through a plate glass window trying to avoid me. Now that is way too much multi tasking……..;-)
I’ve only had experience clocking hardware loops, The looperlative does this really well, without the need for a midi patch bay, If each person was using a midi foot controller that had thru capability. Most good ones from the FCB1010 on up do. Each person needs to be on a different midi channel, and each person has to have a preset for sync record/overdub for the master, and midi sync record/overdub for the slave.