We've been paying for PHI for 6 years, but I'm going public for many reasons:

There's a lower rate of intervention in public hospitals.
I like the birth centre model of care.
I don't believe you need an OB for your antenatal appointments for a low risk pregnancy.
There seems to be a $1000 - $4000 gap for the OBs here.
I trust the nearby tertiary hospital over a privately run business.
I don't care about what my friends think about going to the 'best' private hospital, and having the OB that everyone wants.