If you notice the circle patch panel, a small portion of it was MIG welded while the rest of it was TIG welded. The immediate difference is the weld profile. The TIG process lays a flatter weld puddle than the MIG. The arc from the TIG welder is more concentrated and does not disperse as much heat as the TIG. That's not to say there is no danger in warping the thin metal doors, because warp they did despite our best efforts. The door skins are approximately 22-gauge metal. Metal that thin can build up heat in a hurry and warp if it is not cooled down quickly.