By comparing specs from various sleeping bags it seems obvious that a 850+ fill would be "better" (warmer/weight although more expensive) than a 700-800 fill. Now, if I had the money (which I don't) I would just buy the bag with the best possible down, that is 850+, and think I made the best decision. But is it the "best"? What are the compromises? Do they last as long as "lesser" down? Do they need extra care? Or is it simply better in all regards (except price of course

Also, I like the idea of lighter bag combined with jacket/pants sleeping system that can be used around camp as well. As I know down and water doesn't mix would it be really stupid to go for a down bag + down jacket/pants (and even mat)? Would it be more sensible to combine a down bag with synthetic jacket/pants. Or am I too paranoid? I'm really for the light/ultra light approach but I know Tasmania well enough not to go overboard so again, compromises. What do you think?