Hi @Delfin
my opinion
life is so uncertain.we might need a treatment anytime.as you know health service is very expensive is in Australia.before you think about your visa ,think about you and your family ,if you fall a sick it's very expensive,might end of spending lots of money in order to save may be $200 a month.its more for your personal assurance.
i have seen many people even after getting 887 visa ,still having Medicare people hesitate to cancel their private insurance.i guess you have already spend a lot of money in order to get pr.so why please don't take a chance.keep a private Health for a safety of you and your family and may be to maintain your 489