So, things that I would have liked to have known before starting the transition to Fyx from Vodafone.
1) Your phone line needs to be connected to the Telecom wholesale network. Even closing the Vodafone broadband account and keeping Vodafone as the phone provider isn't sufficient for Fyx if you are still in the Vodafone Red network zone. This is because the phone line connection will still go to Vodafone hardware which can't be controlled by Fyx. I'm currently in the process of moving to Telecom for the phone line and will then use Fyx for broadband. There are probably other phone providers that use Telecom hardware but $41 for a bare phone line seemed pretty reasonable. Telecom even waived the transfer fee. Alternatively you can pay the extra $$ for a naked Fyx broadband connection but that no longer makes the price point attractive if you are also paying for a phone line.
2) Don't cancel your broadband until your phone line has in fact moved over to Telecom hardware. It might take up to 3 business days to transfer from your current phone line provider to one that uses Telecom hardware in the exchange / cabinet (assuming you want to keep the same phone number). I came very close to being without internet for 5 days.
According to the support staff at Fyx this is also a problem for any Orcon customers that are connected to Orcon hardware. Probably also an issue for any internet provider with their own DSLAMs, e.g. perhaps also Telstra.
A bit disappointed that moving between ISPs is still pretty painful for the consumer. Here's hoping that the Fyx broadband speeds are at least as good as Vodafone...