The KLR650 is better than a DR650 on the highway but not by much. Mines got the touring screen helps a lot. It's smoother than my DR650 too. I don't know why only being able to go 80mph is a big deal I never ride over 70mph, no speeding tickets for me. I have heated grips on mine also that'd be nice for commuting.
Not that it matters now, the OP Steven has apparently moved on from KLR's, DR's and such. Sorry for going Off Topic!
Feed back from dozens of DR650 (former KLR owners) riders from big DR thread and many former KLR now DR owners confirms the DR is the smoother engine. Pretty unanimous. The KLR feels strained at 70 mph, the DR is in heaven and really OK at 80 indicated.
My guess is your $1500 DR650 may have a bunk drive line, something not right or worn out?
I've had 3 DR650's, all pretty smooth at 70 (indicated) Pretty much common knowledge in KLR/DR communities. If set up right, DR is pretty smooth at speed.
Windshields can help if they don't cause buffeting. Many DR guys run them, I prefer NO shield for quiet, buffet free riding. Plus .. how can you ride off road with a shield on there? Can't see with shield on there.
I rode a BRAND NEW KLR from Bay area to La Paz, Baja, then another 4K miles all round coastal Mexico including Copper Canyon, then home. 6500 miles in all.
Hated that bike at 70 mph, ended up going 60 the whole trip cause going faster was irritating. Even brand new ... that KLR used OIL ...
TIP: they all use oil.
As for road speed, trust me, riding highway 5 you won't get a speeding ticket going 80 MPH. If fact, you pretty much have to average around that speed just to stay out of the way of the many MUCH faster moving cars.
I've ridden it on my DR650 from Bay Area to Mexican border straight though several times. Usually middle of the night to avoid traffic through L.A. Nothing like morning coffee in Tijuana.
But yeah if you can get a twin at least would be smoother. I was looking into replacing the KLR with a Super Tenere, but decided I'm just going to keep the KLR. It can do some dirt and is a blast in the twisties and it can carry a buncha stuff. Only thing I that bugs me is mines an oil burner.
Ha! Oil Burner? NO! You don't say!
I remember when Kawi used those funky colors! LOVE It! Sure, keep it. It's a good back up to your DR. It's not worth anything so selling would not bring much when talking about a $14,000 1200 Tenere'.