FWIW I rang CASA and the response I was given (after some deliberation) was that I can continue to fly twins and singles under my CAR 5 licence but once I get a part 61 licence I won't be allowed to fly singles any more until I do a SEA flight review.
So gaining/renewing a qualification will allow me to do less.
BTW something to watch out for those who have been keeping everything current with an annual MECIR renewal: Next time you renew your IR in a twin you can't fly singles anymore until you do a review.