Like any machine this good idea does have its limitations.
Since bicycle and motorcycle style wire wheels are not designed to resist lateral loading they are not capable of capable of resisting much lateral loading. Unlike a motorcycle 3,4 or 5 wheel configurations generate lateral loads when cornering. Look how out of true the drive wheel is at the 30 second mark in the video and one can see the need for a stouter drive wheel design in a production model.
I could imagine tearing off, or deforming the frame should any of the other 4 wheels encounter a trailside "stoppie" like boulder, tree trunk, rock outcrop, etc. Frame and suspension arms do not look capable of resisting much impacts even if entire structure is featherweight.