I asked a similar question during Info Day at UWS Parra. I asked whether it was easy to transfer from Adv. Sci. at UWS (Parra) to Medical Science at UTS, and what the criteria was. Apparently, you just need to maintain a high GPA. Also, a factor that would influence your transfer to USYD is the DEMAND of students who want to get into Medical Science at USYD, in which there is quite a lot of competition to get into that course, as those students who didn't get into Medicine area taking it as an alternative pathway.
Hope that helps.
GOOD LUCK!