If interested, here is my user experience, including adding Australia to the "Tomtom navigation" feature on the Sony XNV-660BT.
My Sony XNV-660BT is a US version that I purchased as second hand on eBay, unavailable in Australia, $1000 cheaper than the better suited UK/Europe version.
As purchased it contains a map of USA which is of no particular use to me in Australia.
I tried the "Tomtom Home" App to upload the XNV Australia map, but this new device could not be linked to my existing Tomtom account for my Go730, which uses my email address as user ID.
I had to create a new account with a new/different email address to get access to the XNV maps.
A link then took me to a "Browser interface", which recognised the Tomtom navigation module as being connected by USB, and showed all of the world maps that were available for XNV navigators, of which Australia and New Zealand are listed. AUD $99 each.
Proceed to checkout without further problems and complete the download via an email link sent to my new email address.
There is still capacity on the module to add the Australia map without deleting the US map.
User experience: extremely satisfied.
AM and FM stations are normal
Navigator has a nice crisp display that is easy to see in most light conditions, and same look and feel as my old Tomtom.
CD player is good.
For iPod connection, I have the XA-110IP interface
USB socket, .... SD card becomes the equivalent of the 10 CD stacker.
BT hands free phone,
DVD is unimportant to me, I made no attempt to connect the handbrake wire, also, it is wrong DVD region.
Sony unit was second hand, 2 months old, mostly as new, I paid $300 shipped to Australia, plus $120 for the Aerpro steering wheel connection, $25 for the NTSC camera, and $99 for the Australia Tomtom map.
For a spend of around $550, even the wife says it is amazing....
Thanks to all the Forum posters for the inspiration.
Regards from Dave.