The welding demo vids... is it just me that thought they looked to be an oxidised mess? Intriguing but unless they can do something about the bulk of the 'torch' i can't see it being able to replace anything as currently it looks like it'd be stuffed access wise half the time
It is definitely big and clumsy and i reckon it would make the arm ache after a wile, but it would get in places where you could not get with two handed work, as with TIG or Oxyacetylene. I guess its the old swings and roundabouts scenario really.