Forum Moderators: Robert Charlton & goodroi
I would probably keep the forums on the .com.au domain, they're 11 years old now and I just worry shifting databases would be a nightmare (and expensive).
Unless you've done something ghastly like hard-coding your domain name on thousands of separate files, changing names should involve absolutely no internal work beyond one quick global replace in htaccess.
Bear in mind, you will likely break your software installations by doing this and you will need to fix them (it's well outside of our support scope for such third party scripts).