Insulated Garage door panels for shop walls

I am in the process of getting a farm shop built. I called a spray foam insulator today to get some prices on insulation. WE got to talking and  he started talking about selling me some garage door panel seconds that he gets from a supplier. He can supply me with 16 ft long panels. Basically stand them on end and screw them to the wall.My ceiling will be 16 ft. After the panels are installed he spray foams the back of the panels prior to installing the exterior siding. He can supply the panels to me for $.60/sq ft. Tradional seconds of metal siding runs $.40/sqft. About the only downside I see is the panels are 1 3/8" thick so I will lose some space and there will need to be some additional trim work done around door and window openings. the other down side would be the panels are pretty much captive and would be difficult to replace.

I didnt confirm this but I assume the panels are different colors so they would also need to be painted.

What do you guys think? 

Insulated Garage door panels for shop walls