I must fight Blur with the power of Digic. http://www.digicpictures.com/movie/eng/popup_WHTeaser_high.html http://nofatclips.com/02008/04/27/march/Warhammer%20Battle%20March.mp4
Roughness values should always be in linear space - you will get inconsistent results with sRGB. In terms of reference, have a look at this: https://seblagarde.wordpress.com/2014/04/14/dontnod-physically-based-rendering-chart-for-unreal-engine-4/