We went through this same thing last year. Before that I was devoutly PHI.
We went down to one wage and in the 13years we'd had it, we hardly claimed a thing - less than a year's membership we got back. The premiums just kept going up and up.
We don't use the extras cover at all so we could have just gotten rid of that, but in all honesty hospital cover alone isn't that much cheaper.
We had always kept it before because we were over the income limit and would have had to pay the medicare levy (which was more for us), now that arguement was dead in the water we reassassed.
We got rid of it. Both of us are over 30 so yes there would be a levy applied should we change our minds. We have a little self insurance fund (well it's not little but it's for just incase IYKWIM?). Where we are going to live in the next 10years there is no private hospital or private surgical facilities and like you any baby we have will be had under the midwife/hospital system.