They Have Control
I was based for 5 years as an FO in Sydney. The roster although great at the moment on this base it can change. Many months can be rostered with 12 days at home and frustratingly quite a few days off in Hong kong. These days in HK arent required but just allow the company to have a form of reserve that they dont roster and therefore dont count toward the yearly reserve maximums. I would think carefully about the effects on family and friends only seeing them maybe 10 days a month on a bad month for the new lower pay scale.Also think about your ability to cope with flying with other SYD FOs that would be earning 150-160k ++ doing the same job. For me that would be demoralising.
All the best