I did pose this question to Show Hauler on why they use the structural board over plywood. And they will probably get back to me later today or tomorrow.
My sole reason for moving into a truck conversion motorhome was to get away from traditional motorhome manufacturing processes. This is just my reasoning, I am not saying a TC mfg'er are bad for using these processes, just what I was looking to get away from. Show Hauler was by far the only guy who went so far above and beyond traditional motorhome manufacturing processes that my decision was easy to go with them. They have some of the items that set them apart at the below link.
The Show Hauler Difference
2003 28' Show Hauler Motorhome on a 1995 FL 120 completely refurbished chassis.
Currently in production - scheduled completion 12/10/02 www.showhauler.com