Don't even consider doing it inland. Sydney is moving very quickly at the moment and it's highly likely you would have PR through Sydney before the first stage is completed inland. There's people in this thread that have received their confirmation of PR in 3-4 months, most seem to be happening within six months.
The spreadsheet is here:
https://docs.google.com/spreadsheet/ccc?key=0AmVlTaJuxc5kdFlsVkRfVFVOTWtCYjVjdU9tR1o2aXc&richtext=true#gid=0
It's not very useful (in my humble opinion) because so many of us haven't had our info added. When looking at the spreadsheet it also pays to keep in mind the fact that for several months of this year visa officers were on strike, which slowed applications down. The posted processing times for applications through Sydney were last updated during the strike. Prior to the strike Sydney had processing times of 8 months. This means 80% of applications were completed
within 8 months. I suspect that the next update will show Sydney's times are back to normal or even less.
I hope this helps with your decision-making.