I'm not sure how your ATC handles it, but over here prior to vacating controlled airspace ATC advise you of any IFR traffic affecting you out side of controlled airspace
They don't here - they might (or might not) be able to see traffic OCAS on a radar screen, but they'd have no way of knowing its flight rules.
Many hobby fliers rarely enter controlled airspace anyway, so rarely vacate controlled airspace - it's quite often quicker and easier to go round class D than negotiate a transit.