I have been using the Rohloff hub on my main bike (a Thorn Raven Tour) for the last eight years and I can't really recommend it enough. If I was going on a world tour I would certainly use both the hub and the bike. I don't think you'll have any more trouble getting replacements for a Rohloff hub than any of the modern mountain bike groupsets if you are out in the back-of-beyond. People there will probably be using the cheapest components, if they aren't just using singlespeed.
On a trip like that you probably want a bike that can handle all the luggage without a whimper, and my Thorn definitely did that last summer when I biked across the Icelandic highlands.

Magnus Thor
Iceland