Highway on a 690? Fear not!
As to, being a, "maintenance tech" bike, . . . its heart is a coalition of COMPUTERS! Few of us shade-tree mechanics have the test equipment for comprehensive diagnoses; much less the knowledge to fix what ails it.
Not to gainsay the configuration; after all, most automobiles today have computerized electronics beyond the grasp of ordinary, untrained mortals. We drive THOSE, don't we?
Sophisticated lash-ups want knowledgeable, sound repair. Fuel pump problems? ABS malfunctions? Duct tape and wire ties won't likely resolve 'em.
Just a brief example: KTM690 uses a Hall Effect sidestand safety switch. If the associated components aren't right, it ain't starting, or running, 'cept maybe in neutral. What does a rider do, if this assembly/circuit gets grenaded on the trail? The fix may be simple, but . . . who knows?
And . . . don't think the smaller size of a motorcycle enhances accessibility to components; rather . . . may exacerbate difficulty in reaching critical areas. Example: Brake light switch (one of 'em, anyway) is located 'way down, in the bowels of the beast, close to the ABS magic lash-up.
Back to your questions; vibration? My perception, the KTM vibrates less than the KLR; my estimate may be incorrect, because neither machine's vibration bothers/annoys me; an area where I may be totally insensitive.
How does a 690 compare to a DR650? Don't know, but . . . I'd bet you could substitute "DR650" for "KLR650" in the comparative analyses above and reach similar conclusions, performance and operational capability wise.
Again, as to on-road performance of the KTM: It's fast, quick, nimble and maneuverable beyond realistic KLR650 expectations, with shut-'em-down-in-a-hurry brakes (with switchable ABS). I'd say, overall, the KTM appears safer on the highway than a KLR . . . provided you don't attempt to set the World Land Speed Record on your commute; and . . . believe me, you'll be tempted to try it!