Camera weight isn't an issue, it's the size, and how obtrusive it is. With the 20D if I wander to the beach the camera takes a bag for protection and to hide it, plus whatever else I want with me. With a P&S I probably won't need to take a bag at all. Losing it isn't really a big issue, insurance will cover it, it's more than having to take a big camera with me.
Of course I could take both, that way I can take the P&S when I don't want to bother with a big camera, and the big one when I want to take photos.
I'd like a small, 3-4MP ultraslim camera that takes CompactFlash and fits in my pocket. Does such a beast exist?
!!

Anyway I just spent 4 weeks travelling through a bit of New Zealand and Australia (mostly Australia). I did adventure tours in both countries with my backpack and stayed mostly at hostels (I stayed in double rooms with my girlfriend half the time, and in dorms the other half). I ended up getting a G6 to take over my 20D. I too was worried about theft. In hindsight, I wish I'd just brought my 20D with me. There were no issues in Australia. I think you'll be ok as long as you're not careless with leaving stuff around unattended. 
