From memory, I don't think there were many mid-sem courses that you could transfer to in usyd, mainly just Arts, Science. Though if you want to do Com/Eco, I've been told that UNSW is better *cough*.
urdy and sarevok: Thanx guys, you've just made my day I knew something was wrong when someone told me that there were mid-year transfers... Actually, it wasn't wrong, just the wrong faculties. Only UNSW currently has Com/Eco mid-year transfers.