Replying to this really quite late - but I'm checking this out as I'm about to fly OS.
Here's the yet another answer from ABF:
Personal goods
The following personal goods are free from duty and tax
- personal clothing and footwear (excluding fur apparel)
- articles for personal hygiene and grooming (excluding perfume concentrates)
- goods owned and used by the traveller overseas for 12 months or more, such as
- personal effects, furniture, household goods and fur apparel (excluding alcohol and tobacco)
- goods imported temporarily (note: a security deposit may be required by ACBPS), and
- goods that were previously exported from Australia (excluding goods that were purchased at a duty-free shop in Australia or goods for which a TRS claim has been made).
Source:
Australian Customs and Border Protection Service - A guide for travellers, know before you go
It goes on to say:
If you are considering bringing goods back to Australia for which a TRS claim has been made, you should declare the goods and may be required to pay back the GST refund. Penalties apply to undeclared taxable goods.
So they do seem clear that you should declare.
I'm still inclined to read the very clear instructions on the Incoming passenger card - because that's what I'll be reading just before I hand it over - and it's pretty clear as well:
Are you bringing into Australia:
3. Goods obtained overseas or purchased duty and/or tax free in Australia with a combined total price of more than AUD$900, including gifts?
The answer to that question will be "No".