Thanks guys for your feedback. Another dimension to this.
If I am an Australian business targeting Australian customers but host offshore. Does it matter from an SEO point of view if I use domainname.com or domainname.com.au? I understand it may impact what the customer thinks but I am more interested in it from an SEO perspective and if the domain extension is important.
Further does the registration address (i.e. whois data) matter. For example we are Australian based but our domain registration address is in the US.
I assume these are all subtle things but I am interested to understand if they have an impact on SEO.
Thanks