If those are the bikes you have chosen, then test ride, test ride, test ride. Its the only way to get an idea of what is the best bike for you.
To be honest, if you are doing 10% off-road (depending on how severe that off-road is) you might was to consider a more road-biased bike. You'll be a lot more comfortable, and probably have a bit more power to play with (two-up may be a bit of a load for a 650) for most of your journey. Otherwise, you compromise 90% of your KMs to make 10% a bit easier, unless the off-road is very difficult terrain....
Just something to consider.
Adventure: it's an experience, not a style!
(so ride what you like, but ride it somewhere new!)