Definitelly Down Hill MTB. It's really awesome. It can be very challanging if you want it to be. Also count on having to spend few grand once you taste how great it is (which will be totally worth it).
The best thing is it's more reliable than wind.
And when you try it out, do'nt just do green runs... find some place with blue and black runs. You don't have to go fast the first time, but it will give you idea what sort of thing you can do there. Australia has so many MTB trails to explore almost everywhere you go.
Next thing you know, you'll be carting your bike to overseas trips like I did
