Lots of riders, myself included, moved on from a KLR to the 650 strom.
Highway travel is great, comparatively. I've done quite a few 500+ mile days on mine. Revs from 65-75 will be anywhere from 5000 to 6000, and the engine will cope just fine.
The Strom's handling is one of its strong points. It hands-down beats the KLR on twisty roads and is a lot more fun while delivering the same fuel efficiency, and longer wearing with a stronger engine.
The strom should last over 100k miles easily without needing a rebuild, and I find that it's easier and cheaper to maintain. The tires last longer (and are tubeless, thank god), the oil change interval is longer, and you don't need to mess around with a carb.