Chemo is chemo, Melissa. It's all pretty standard and if you have confidence in your oncologist it should not matter where it is delivered. They are not chefs; treatments are very clearly defined and apart from circumstances where someone is not tolerating a drug if you are getting FEC (or what ever alphabet soup is prescribed) up there it is exactly the same as what someone in Melbourne or Sydney will receive.
The only advantage the southern states may have is access to clinical trials. That's a double edged sword if you have to travel for them as there is no transport subsidy for trial treatments.
I'm not sure if the quality of radiotherapy treatments varies from site to site or not and have no idea how you would get hold of that information.
Surgeons are another matter, particularly if you want reconstruction. That is something that needs some research when the time comes.