thanks very much for the post i have been wondering about that stuff for the last couple of years.
the part i like is when the two metals are bonded the glue actually seals the seam which you couldn't do after welding a panel very well.

i had been thinking about covering the seams on the outside of the panel with a thin coat of Duraglass and then use regular bondo for the finish work on top of the Duraglass since Duraglass is very hard to sand.

am i on the right track from keeping the bonded seam from showing up in the future?