Sorry, I tried to post in this thread and then the forum went down
I'm not in law, but I know melsc has done law at UWS and then transferred to Macquarie. Perhaps try sending her a PM with your questions, she would be able to give the best insight as she has studied at both uni's.
Personally, I would say stay at Mac. Not because UWS is harder or easier, but because when you repeat the subjects, you will be familiar with the subjects you have already taken at Mac, whereas you wont be familiar with the subject layout at UWS. Plus you'll already have the textbooks and lecture notes you made from the last semester (unless you're unlucky and they change the textbook or redesign the course structure!).