Summer 2012 I did 2600 mile ride from southern Colorado up into Montana and back on my MRR. Here is the trip report:
http://advrider.com/forums/showthread.php?t=816701&highlight=hopscotch
The WRR was just fine.
I added Lynx Fairing and windshield with HID headlights. Very nice. Aftermarket seat. 4.7 gallon fuel tank. Wolfman luggage rack and luggage. Home made tail rack from plastic cutting board. Wolfman tail bag. All luggage water proof. Wolfman tank bag. As you can see, I really like the Wolfman gear. Nice stuff. I did add a stiffer spring on the rear shock to carry the weight of me and luggage.
My brothers DR650 did great as well. That would be an excellent option. 50 or 60 lbs heavier than the WRR. But decent horse power for highway and lighter than your current bike. Also a very reliable bike.
Check out Big Dog Adventures web site. He has done over 50,000 miles on his WRR and it is still doing fine. The one mechanical item on the WRR to worry about is the fuel pump. You might carry a spare.