Don't get me wrong, I'm a Diablo addict for sure, but... my honest choice would be (and that's also what I did when I travel) to not play Diablo. I've waited for Diablo 3 for years, even bought a new computer in advance hoping I would get beta access. Nothing. Then Diablo 3 was released a week before I left on a 3 months internship... so I basically missed the first 3.5 months of Diablo 3 after release. Absolutely no regrets. Getting into a new culture (and especially enjoying the freetime activities with all the new friends you'll make there) trumps even your favorite video game. You will not remember S8 as much as you will your stay in down under when looking back in 20 years from now.
That being said, maybe you have your reason why you still want to play. I'd probably switch back and forth, there are good reasons for both: on EU you probably want to get the stash tab. But you'll have high latency and play during times when people are offline. On NA you have the chance to meet people from your new home and might in general have more people to play with. But since the AUS/NZ server is on the NA realm that might be a mixed bag. So yeah, my preference would be: 1) Not playing at all, 2) EU, 3) NA.
As I am a casual player and continue to play, the time I will use on Diablo will definitely decrease because there are a lot of things to see here 'down under'.
normally play Diablo during evenings on weekdays to get me head cleared from school/job and will continue to do so. But yeah... Not sure how Diablo will rate compared to the freetime activities, when I get started on those.
i will play eu then, get the stash space and perhaps that is all I will achieve in this season.
there must be playing in Europe servers from AUS and NZ?
So that you're clear, you can play on the European region from Australia
And as you are aware, the AU server is tied to the Americas region, but even if the AU server was tied to the European region in anyway, if the host of the game is outside of Australia, you will still get bad ping. This because the game instance is hosted on the server closest to the leader of the party. And if you were the host on the AU server, all your EU friends will have bad ping so someone will lose out because of the geographical distance.
But I concur with the advice on getting out and about more while you're in Australia, and just spend the 40-60hrs getting the stash tab in Seasons so you don't miss out.
And yes, there are lots of animals in Australia that can kill you... you just need to be mindful of these things depending on where you're venturing to.