I'm leaning towards Amaysim too. Be interested to hear about your experience.
I've submitted a complaint using the online form but not really expecting any joy. On paper the low cost/prepaid operators plus either their roaming option or an ad hoc local/specialist esim (I have a dual SIM phone) should work out significantly cheaper than what I'm currently paying Optus, and much cheaper again than the new Optus plan + a daily roaming charge.
I have no immediate o/s travel planned, so thinking I might hop around through a few of them for a couple of months taking up their new customer offers to try them out and then settle on a long expiry prepaid plan with one of them.