What's really the difference sound wise to create a paraphonic synth by running multiple VCO's all into the same VCF, VCA, EG versus "true" polyphony though? With some affordable VCO/DCOs and a MIDI to CV converter capable of routing the various CV inputs to the VCO/DCOs; it seems very doable in modular, especially compared to the massive rigs with expensive digital modules people put together without complaining too much of the cost and complex patching.
I would think tuning / calibrating it might be a pain, kind of akin to playing that guitar you keep lying around but can never quite get in tune with itself 100%.