I use a single style cutter from
www.hougenmfg.com called a Rotacut sheet metal cutter. I just put a dimple with a centerpunch in the middle of the weld( and sometimes do the drill thing ,too) and a few seconds later it's done. They're almost like the cutters shown on the bottom of your link. Most of the bodymen I know use the solid, drillbit style, as it doesn't leave as much metal in the center of the weld like the circular cutters do. Just a matter of preference, or experience, I guess.
RicG