Thing is, until they've seized and inspected it, they can't tell whether my device contains relevant data or not. I'm not confident that keeping separate devices will protect me from the exigencies of discovery.
If you end up in a situation like that - which does not mean you did anything wrong at all - your best bet at getting your personal data and items back is by 1.) having them physically separate 2.) not encrypting anything or immediately providing passwords / access so items can be cleared.
Effects and results may vary. Consult your local lawyer for more information.