Power outages?
We need to know how NBNCo plan to allow for power outages. If they are planning to decommission the copper telephone lines and force everyone onto VOIP, then the HFC network will need power backup and there certainly isn't any on Telstra's current network.
The FTTP network, being passive, will allow VOIP calls in power outages since NBNCO supply battery backup to residences and we can't be creating a digital divide and second class NBN citizens ...