That's not entirely right cabinboy... it is true that you cannot transfer to mainline QF from Impulse. That of course does not mean that Impulse crew cannot apply for Qantas if and when it becomes available - however they will have to resign their position at Impulse and they would go to Qantas as if they had only just started with the company.
Other subsidiaries do not work the same way. Employees of Eastern, Sunstate and Airlink are able to move to mainline Qantas after a qualifying period. Also if you do move to Qantas then your previous years of service count. If you can't wait until that qualifying period is over, then you can apply for Qantas externally but you will go over as if you had just started with the company.
That is my understanding, I am sure DASH would know more about this though.
SG