I've been using KeyShot for a while now and I find it's material system very intuitive and powerful... And although it does not support true multi-layered materials yet, I've found that by using labels in conjunction with conventional materials you can achieve something similar.
You can see this in 'Steel with fingerprints' and 'Dented DuPont paint'.
The other renders do not use labels, but use a combination of diffuse and bump maps with differing levels of roughness for the metal shader itself.
Most of the maps were created by myself, apart from a couple and are hi-res, 2048 x 2048 seamlessly tileable.
These are just a few of the metal shaders I've created for KeyShot, I will add more here when I can. Each render has 2 shots, normal and a close-up.
For viewing, may I suggest 'downloading' the images, you'll be able to see them at their full size and quality.
Thanks for looking...