Egads - it'd be just my luck for weather and strikes to affect the delivery of the most expensive package I've shipped OS so far.  (Buyer is in a south-eastern state, though, so hopefully the weather won't affect delivery).

Re: the difference between registered and pack & track... Registered is typically not trackable in Oz, and gets a signature on delivery (as you know), Pack and track can be tracked via AP from start to finish, and doesn't get a signature on delivery - as far as PayPal and eBay are concerned, an online status of delivered is as good as a signature for packages under $750 (including postage), as long as you also have documentation to show the delivery address. There used to be a difference between insurance as well, I have vague memories of P&T being insurable up to just $200 or similar, while registered could include up to the normal $5k extra cover...but I was looking at the service comparisons earlier today and they both have an X for extra cover (meaning it can't be purchased?), so I don't know about that anymore (their charts are a bit misleading though, they have a tick showing you can register an international letter, but when you investigate further, it turns out you can't register a letter, only use a parcel service instead >_> ). 

I'm starting to think registered might be the better option for US orders, it might not be trackable at the start, but if it's trackable when it hits the US and requires a signature, it might help avoid situations where an item is delivered but not scanned.