QR has a system for pilots that have left and wish to return.
Provided you left on a good note, paid your bond, etc they do not hold a grudge and you will be welcome back. I know several pilots that have resigned and returned, one guy did it twice!
As said things have improved a lot in the past four years. Not just remuneration but the whole company attitude has become more relaxed and 'humane' than before. For example, where training used to be punitive there is now extra training available for those that need it, all with the aim of getting pilots to pass. Training here is generally very good.
In contrast to our cousins down the road, we also have 42 days guaranteed annual leave that the company is not allowed to roll over.
A330 LHS and 750hr/year.