Unless you are trying to save a panel, why would you want to use one of those?? My personal opinion is they ALL suck. The S.O.B.'s walk allover the place. I bought mine off of the Snap-on truck. Comes in a complete kit with the punch and several different size cutters and the wrench.
If I am saving a panel I will just use the correct size drill bit for the spotweld that way the holes are ready when its time to reinstall that piece. If it is a panel that will be tossed I just use my old reversable Cut-off tool from the Matco Tool truck with a thin 3M cut-off wheel and grind the top of the spotweld off until you see the first layer of sheetmetal start to roll up. Then tap a body chisel between the panels and Wha-La, Done. In the time it takes you to drill out 1 spotweld I would be thru 3-5 with the cut-off wheel.
Of course time was important to me. I could flag 150 hours in a 40 hour week in a production dealer shop.
Also,
the cut-off wheels are the cheaper "expendable". Those bits are anywhere from $8 on up!