Trojan has hit the nail on the head in this instance. If you are vaguely interested in doing the airline thing (and RAAF being a means to an end), you would be far better served staying civi and joining the airlines as soon as you get the required minimum experience for the various companies.
Don't forget QF runs the seniority system, and as a result all those crusty old (and some not so old) RAAFies that have spent 11 - 15 years in the forces that are pulling the pin and walking to QF start at the bottom of the seniority list the same as little Johnny that's only been flying bugsmashers for 3 - 4 years or so out bush.
There is definately some good/interesting flying to be had in the forces (so I'm certainly not knocking it), but you won't do particluarly much of it (some guys are kissed on the dick and get a good run, goto the right sqn at the right time etc.. most don't). Don't let me even get started on the Navy training pipeline at the moment.
Just a bit of food for thought.