After more experimenting with this set-up I’d add some observations:
- this is definitely the way to go for longer Pick-up-style recording. When using scale mode = per track and the midi track1 scale set to 16/16 you can reliably pick up quantized recordings of any length without having to worry about the dreaded tempo change, or undefeatable time-stretch**.
-There is however one caveat: because the midi message “stop recording” makes a roundtrip (out and back into the OT, in my case re-routed via a midi-interface where I filter out all unnecessary stuff ) the recording might be just a millisecond or two longuer than wanted. This results in a bit of drift over time, because the sample is not periodically retriggered like the Pick-up machines seem to do internally. That’s why for longer recordings this is OK, but for short loops it’s better to use a PUM.
To resync the loop either arm the audio track’s one-shot manually or hit footswitch2 again.
I’m still trying to find a way to automatically retrigger at the corresponding length, but I don’t think that is possible beyond 256 beats unless we mess around with tempo multipliers but then again, I’m a musician, not a calculator 
The whole idea is that you can record first, decide later. With Pick-up machines either you decide beforehand, or, if you don’t you are stuck with limited possibilities and a fair chance you get the tempo change chaos.
** The Pick-up machines seem to be “elastic” Beats are a bit “floating around”, sometimes perfectly timed, but the next beat can be several ms late in the same loop. I suspect the time stretching to be responsible. They are not as tight as the flex machines.
