Even if you get given a BN2 job with SA there's still a chance that they'll send you to Broome or Darwin rather than HID. They won't send you to Cairns though, that comes later--if you want it.
I love my flying with SA, I know nothing about Skytrans, I also know the odd SA pilot who "don't like mucking around low level" and would rather fly RPT. Also bear in mind that the Coastwatch contract only has a little more than two years to run.