In your case you are continuing the same course with the same professor and only need a change of University. So you can request for CAS from the New University which is generally issued 90 days before the course. You need to submit that CAS and can get the Tier 4 visa changed.

If your intent is to settle in Australia & asking which is the better route, there is no doubt a skilled migration is the best route to enter & avail opportunities to settle in any developed country. Your profile seems to meet the minimum requirement for both study & skilled migration to Australia, ...