We used to be with NIB but they messed us around so much, and then even though we were covered for pregnancy, obstetrics, etc, they wouldn't cover us for any of the investigations DH had & weren't going to cover us for IVF. (we had asked to be moved to top family cover in advance of getting married, so they moved us to the wrong level and then messed us around because of their own mistake!) We also discovered, when I had some surgery, that even though I was covered, the amount they pay back is dismal. All the medical receptionists and people who deal with billing all told me NIB is well known to be pretty much the worst of them all in terms of what they pay back on hospital stuff. They pay well for extras, but are appalling for hospital cover.
We changed to GMHBA late last year, fully expecting to have to wait 12 months for the IVF cover, as we didn't already have it & that is their rule. To our surprise, they made an executive decision to waive that & cover us when we did our cycle in Mar/April. I rang when we were starting the cycle, with the item numbers, just to check if we were covered. She went away for a little chat with her manager & rang me back to say, because we'd been so messed around by our previous fund, they had decided to give us that cover early. How very nice! So they covered all my day surgery fees for my EPU and ET (I just paid $125 excess each time, and that is now the max for the year so nothing to pay next time), and for DH's microdissection, as well as part of the anaesthetist for both of us, and part of DH's actual surgeon's fee.
And you don't get given the run-around or wrong information when you speak to people there. I can't recommend them highly enough, although they're a bit slow to pay. Had to ring up & chase the claim.