Most of the Eagle model uses simple two layer Maxwell materials - the base colour (my textures) and one for the sheen. This is nice enough but could be much better. The sheen is the same all over the model but the model also has simulated dirt/dust in the textures that were created by using all the ambient occlusion bakes. Surface roughness should be greater in those areas.

These two blue spheres show this. The left one has a uniform sheen layer across the whole surface. The other sphere has variable roughness driven by a white to black gradient image. Therefore, I will use the raw ambient occlusion bakes to simulate this on my Eagle model.