Hi Reto,
My ArduPilot project came to a stall during late summer and autumn, mainly due to the soaring and then slope gliding seasons! Now that days become shorter (and winter evenings longer, I'll try to finish tweaking this project. So I'm sorry not to be very helpful right now, many have taken the advantage with successful ArduPilot flying experiments. I am sure I'll come up with a completed UAV this coming spring. In the meantime, I'll of course share my experiences in my posts on this blog.
Just out of curiosity: are you going to the Outback Challenge alone from your ZH base or do you already have a team set up for Australia? Don't you need some more partner?

Hey you're pros! You'll probably loose your time looking over my shoulder. I am just an archaeologist taking grasps of online tech to fill my leisure time! My setup is somewhat described in my pages here, and in different posts around. If you'd like the last code versions I experimented with, you're welcome. I can gather them this week and pm them to your aerovista contact email.
Seems you've got plenty of specialists for bringing that outback challenge home!!! by the way, once you get some work/experiment to do with aerovista airfrmaes between ZH and BE (or further West), please leave me a note. I'd like to see you operate in the field. Is it a double Easyglider foamy you're using? Or a double Cularis? It looks terrific (in the good sense of the word, of course).

I choose ArduPilot because it's the first open source AP community I stumbled upon. It was in it's youth, was very promising, and was the most accessible. The "low cost" idea appealed me too. I think it still has great potential, though it may not be the best option for someone wanting to go professional since it's not an out of the box RTF autopilot.