JARs and FARs are simply sets of requirements, and there are an awful lot of them. If you go to the "useful links" page on "tech-log" you'll find links to most of them. They are interpreted within national systems, sometimes differently.
For most of the main standards there is in-fact a joint JAA-FAA committee somewhere trying to converge the standards, or at-least understand what each other are up to. So, in the long run, I don't think it matters much which way a particular country goes since in most issues they'll end up using pretty much the same book.
The big issue really is how a particular national authority elects to use the JARs. A classic balls-up was the UK CAA treatment of JAR-FCL (Flight Crew Licensing) which after some years is still giving most people a lot of grief. On the other hand, the use of JAR-22 (gliders and motorgliders) has been a complete success in ever country I've dealt with. JAR-23 and FAR-23 (normal, utility and aerobatic aeroplanes) are virtually identical (so long as you have no more than 2 engines anyway), BUT it's very clear that the UK and US (for example) treat them with occasionally very different rigour.
So, I would suggest to Australians, speaking from a JAR country, that it'll make no real difference. What's important is CASA's treatment of your industry, which is a totally separate issue.
Incidentally, I've heard rumours that with the advent of EASA, JARs may in-time become ECARs (European Civil Aviation Requirements), although I doubt that anything but the cover sheet and reference number is likely to really change.
G