In tearing into my trailer to make delam repairs (it is the conventional aluminum frame, styrofoam insulation, luan, and fiberglass lamination) I found that what delaminated was not the luan pulling away from the fiberglass but the actually luan disintegrating and the layers of luan coming apart. From that aspect the alternative materials would probably be a whole lot better, but my original point was that there shouldn't be water in there in any case. If you have a stick/aluminum sided trailer, and it leaks, there is no delamination, but the insulation will get wet. In either case, the manufacturers don't seem to take a lot of care in making sure the shell of the trailer, seams and all, are water tight.