I had a XT660R for 7 years:
It was a decent bike, definitely better off road than the Versys, which I consider to be a 100% street bike. But as a road bike, the Versys blows the XT out of the water. The V has more power, better brakes, vibrates less, better seat, better suspension and better handling. Honestly, there is nothing the XT660R does better than the Versys on the road.
You can take a Versys off road, you can off-road any bike, but that doesn't mean it is good at it, not to mention that unlike the XT660R that had soft plastics, the Versys has hard ABS plastics that will break if you take dirt nap.
I sold my XT660R, off road was not my thing, I'm more of a tourer, so the Versys suits me better.