Georgee, sorry I have no knowledge of the PIFR as I have always been too chicken to stumble around IFR in single engine aircraft, so never held such a rating.
My guess is it would depend on the approach minima that the PIFR allows - again, no understanding, but if the approach terminates at normal circuit height with better than 'special' VFR conditions, I would argue no specific extra training or testing would be required as the pilot's BFR covers the ability to fly a normal circuit. It is a little different when flying 'full' IFR to complete a circling approach, which in a cat B aircraft could be flown as low as 300ft above obstacles.
One for the flying school experts to answer.