I have a WR and a DR.....and have ridden both on the Colorado and Utah portions of the TAT. The good news is, is that both of them will be good for the job. I'm 6' and 200 lbs. and carry about 65lbs of gear (including the weight of the luggage).
On the road, you can ride either one all day long....day after day. They are both very smooth thumpers.
My choice for the TAT, CDR, etc. is the WR (with 14/50 gearing and a 13 tooth counter sprocket in my bag). However, my reason for the choosing the WR is mainly because I travel solo, and the WR is much easier to pick up.....and I would have a much better chance of getting out from underneath it if I got pinned. Only once have I found myself wishing I had the DR, and that was on the very high, technical mountain passes in Colorado (think Imogene, Sheep Creek, Black Bear, Mosquito, Marble/Gothic).....the WR had no issues on the TAT Passes (Hancock, Cinnamon, etc.). Having said this, the WR made it....but was lacking power on these high passes. Everywhere else, it's equal or superior to the DR. Overall, I'd choose the WR on a long haul solo
However, the DR may be better for you, because it has a lower seat height....which may be worth the weight penalty relative to the WR. A DR will rip up any of the TAT passes, including the other Colorado passes I mentioned without issue. If you go with the DR, don't bother messing with re-jetting at altitude. Just ride the damn thing.....when you get to high elevations....somewhere between 10-12k feet, simply remove the airbox door (make sure you remove the captive nuts too, or they will rattle out and you will lose them!). After that, the bike will run strong well over 16k feet. When you drop back down....put the airbox door back on....much easier than re-jetting on the side of the trail.
Bottom line, both bikes are great, reliable, long haul adventure bikes.....you won't go wrong with either. It just comes down to personal preferences.
Why oh why won't Yamaha make a WR450R
.....now that would be the ultimate adventure bike!