The Australian government states that dual nationals must enter and leave Australia on their Australian passport. In order to do that, one needs an electronic travel authority (ETA) for Canada. However, the Canadian government (http://www.cic.gc.ca) states that dual nationals cannot apply for an electronic travel authority and must have a valid Canadian passport to be allowed onto any flight into Canada in order to board. Does anyone have recent experience with this? Do I need an ETA for my Aussie passport? Or can I do the whole trip on my Canadian passport and just show immigration my Aussie one to prove residency?
The recommendation for dual nationals (of any nationalities) is that you enter/leave each country for which you have citizenship using a passport for that country.
If you have Australian/Canadian citizenship, that means that if you are flying from Canada to Australia you use your Australian passport to check in to your flight, then you leave Canada using your Canadian passport. At the other end you enter Australia with your Australian passport.
The reverse would apply when flying from Australia to Canada: Check in to your flight using your Canadian passport, leave Australia on your Australian passport, and then enter Canada using your Canadian passport.