The QA Hackathon sounds very interesting. The flight to Oslo isn't expensive (at the moment), $job and @family don't object. But: I hate flying. It's uncomfortable, and it's bad for the environment (and I already totaly blew my CO2 balance last year with my trip to Mongolia...)
I have to decide soonish, before the ticket prices rise... Hmm...
A train isn't as fast and will likely take a bit longer than a day, but it could be fun. It would be good to see you there.
Train takes something like 38 hours (one direction!), which is a bit too long for a few days in Oslo.
I will go by train to Copenhagen for YAPC::Europe (which takes a night and half a day and thus is reasonable).
But maybe I'll just go for one of those forest-planting thingies, thought I doubt their effectiveness. And it's basically Ablasshandel [wikipedia.org]
I could engage in some CO2 footprint relativism - like at least your trip has benefit to a wider community - but as Curtis says, just get the train or something and BE THERE
I don't see your dilemma.
If I can fly there from Sydney, I'm sure you can fly there from Europe.