To each his own, Pat. The fitting time on a butt weld is twice that of a flanged seam. I use metal to metal for the first coat of filler which seals out water and seam sealer or the back side of the joint. If the seam is worked properly with a hammer and dolly, it is no more apparant from the back side of the panel then a butt weld....... Actually if you tig or mig the flanged seam correctly it requires a minimal amount of filler. JMO, like I said, to each his own. No one method is bettor or worse then the other if done properly...