I've been experimenting with material creation in different software. After looking at a procedural texture video from Naughty Dog and skimming through a somewhat similar walk-through from James Sky, I decided to create a texture purely in Substance Designer and test is in Unreal Engine, Unity and V-Ray.
After exporting the textures I did a bit of research on Unity material set-ups following a useful Calibration Chart on how the Red channel and the Alpha are used to produce the final material in Unity. Unfortunately the metal/roughness did not work and instead of adjusting the maps in Photoshop, I just used the metal/smoothness sliders to achieve the final result. The Calibration Chart also mentioned the Diffuse/ Albedo Luminosity Median which I adjusted in Photoshop.
The final results can be seen below. UE4 lost a lot of diffuse and AO despite adjusting the sRGB setting and AO baking. It was also a little flat due to a lack of a height map. I may be able to multiply the normal map.. Unity used a normal and height map with made a big visual difference but needs further adjusting. I might have better luck with the Specular/Glossiness set-up. The V-Ray sun gave the scene a warm tint which could be adjusted in the filter settings. It also lacked depth much like UE4. Further experiments are required. It was good getting back to V-Ray though.