I just finished taking apart the small slide in my 2004 Gulstream Innsbruck. This meant taking the entire skin off and the interior wall coverings, removing and replacing some of the framing and replacing the floor.
The factory installed floor of my small slide was solid 1 1/8" Marine plywood. (Covered in black plastic on the underside which was the cause of much of the problem)The walls were made with 2x2 lumber with a header of individual 2x6's over the window.
When I went to look for 1 1/8 plywood of ANY kind there was NONE to be had in Minot period. I ended up making the new floor out of a sheet of 3/4 Marine plywood with a sheet of 3/8ths non marine plywood glued, screwed and stapled together. I put the Marine plywood on the bottom exposed to the elements (when deployed) and used the non marine 3/8th for the "top" or inside. I primed and painted and polyurethane'd the underside, edges and a bit of the top and did not replace the water/moisture trapping plastic sheet.
The insulation was not great but adequate. I removed it and replaced it all.
I can tell you there were MORE than enough screws and staples in this entire assembly to sink the Titanic. And they were not cheap coarse thread galvanized screws. They were for the most part fine thread high quality steel. However some had rusted over the years due to a water leak from an earlier time that had been successfully repaired. Unfortunately some of the structure having been left wet at the original repair did Dry rot.
As for screws vs staples. In every case I dealt with the staples lasted longer and were very strong, holding better in most cases than screws would have or did.
It was also interesting to take this slide apart and see in what order it was assembled, making it in some cases very difficult to take apart at all.
My judgement on the Innsbruck after this is that it is made to a very good standard of construction quality (in 2004) with quality materials and good workmanship considering the time constraints in a production line setting.
There is no OSB or particle board in the entire trailer as far as I can tell.
This project was very instructive and while my repairs made it ultimately stronger than it was originally it was still very well made at the factory.