Ok for performance based stuff the OT is king. Sampling on the fly and messing with those samples is its strong point in my book.
Do I understand you correctly that you would want to jam primarily with sampled loops that you produce on the fly? (ie guitar, bass, OP1 — any other sound sources?) Or would you want to also midi sequence any instruments on the fly?
My tip would be to attribute a specific purpose to each box as you are already in the process of doing.
For example:
OT = sample recorder/looper & mangler
OP1 = Synth / Sound source
MPC = (what do you envision here? :))
The other tip is to preset your samplers (OT/MPC) with a set of sounds (a sound palette) that you then stick to and experiment with. Often the flexibility of something like the MPC can kill all spontaneity. You could for example set up a track for drums (and create a specific drum program on that track), one for synth-y sounds (and create a specific keygroup program on that track) and maybe one track with one shot samples of all sorts (vocals, textures, etc). And then you stick to those for a few weeks before you mess with the sound palette again.
Ok all that said, here is a suggestion on how to integrate the three devices:
I would probably run the guitar and bass straight into the OT (so you can loop them easily) and set up a Thru track to handle those two coming in (so you can add FX to them – if you want to treat your guitar and bass separately, you’d need two Thru tracks). Then I’d run the OP1 into the MPC Live and two outputs of the MPC Live into the OT’s Inputs CD. Now you can loop anything you play on the OP1 or MPC right in the OT and keep the vibe going (or mangle the recordings into oblivion :)), while you can also sample the OP1 in the MPC in case you wanna perform any of its sounds via finger drumming.
You could set up the OT’s track 8 as Master Track which would also give the possibility to affect all signals running through it (hence: your complete setup) with FX (reverb or some form of mangling).
If your OT sequences your MPC via midi, you could use the OT’s LFOs on your MPC’s sounds as well to add modulation / movement.
As you can probably see, the possibilities and choices to be made are many, but what I describe here is likely a good setup for live jamming if you want to start from scratch and build soundscapes in realtime (it’s what I mainly do as well).