I never heard of this. So, do you just glue the new panel right over the old one or is some of the old one removed like with welding?
I would think you are creating pockets for moisture to sit in between the two metals. Since the bottom metal is already rusted through it will quickly "infect" the new metal. I would think it won't last as long as a proper welded in panel. A welded panel is basically goes in place of the original metal with no nooks or crannies for rust to develop. Condensation etc won't have a place to live on a welded panel.
