The Jayco website has brochures going back to 2003.
Brochures | Jayco, Inc.
I looked through a few of the 2003-04 types and don't see any with "all aluminum" construction. The models with composite walls all seem to use aluminum framing and those with aluminum siding all seem to use wood frames.
While my J-feather has aluminum framing, I really don't see any long term advantages over wood. You need to fix leaks quickly no mater what the underlying structure is and dry wood does not rot. We had a 25 year old Winnebago with wood framing that was in great shape when we sold it to buy our Jayfeather.
Thin walled tubing is not easy to weld. Aluminum gets much of its strength from heat treatment and the heat from welding greatly reduces the strength in the areas of the welds. My experience with aluminum weldments is that if one weld fails, a lot of the welds will fail soon after. Fortunately, the welds would likely fail very soon and the trailer would still be under warranty. I am not at all worried about our aluminum framing.