This may or may not be relevant to you and your style of riding, but several of us have blown up freehubs on our fatbikes. We attribute it to the massive amount of power you can lay down without any loss of traction. For that reason, I wouldn't ever ride on an internally geared hub - personally. There's also a misconception that internally geared hubs are simpler, and less prone to trail damage than a traditional derailleur. Not true. Internally geared hubs still have a long way to go in terms of durability. This excludes the Rohloff hubs, but those things are so heavy its crazy. Mine sits in a box in the basement because it was like riding with an anvil in my wheel.