The Vario is a clever bit of kit, and in short-mode, doesnt look too bad on the XR - and just requires the vario plate screwed to the rear rack of the XR.
But - the vario is heavy, even when empty, so I’d avoid it for that reason, unless it was in short-mode with just waterproofs , a puncture kit and perhaps a camera.
Looks crap when extended to full capacity.