Hmm. I'm actually not sure how far I am going to get. I'll definitely be on gravel for a fair while in Alaska, and I'm intending to head south through Canada, but I'm not sure how far south I'll go, so I don't know how much asphalt I'll encounter.
Perhaps it's just best to go for the middling option, assuming that half the time I'll be on gravel and the other half on asphalt. This would mean I should get XR front and rear, right?
(And I'd be on my own, so perhaps the Campbell is a little risky?)