Sure, you’re welcome
Thanks 
Few more explanations I didn’t mention before:
For specular, roughness and metallic don’t be afraid of using negative values. You are multiplying the texture at the end, so this way you can darken it.
Sometimes it can act weird if you have too contrasty textures. Better make them a bit more grayish/washed out.
Or you can tweak texture values in their options, likewise it’s better to use not sRGB for composed textures and for splatmaps.
The shader is done the way, you layer up only the enabled options, otherwise it takes the values from the layer below.
To give an example;
If you have layer 0 diffuse and specular enabled, and for layer 1 only diffuse, you will have as a result diffuse of both and specular of layer 0 only.
I hope I explained it right…
For mask you can use multiple options at the same time. It will all lerp together.
On the side note precomputed AO doesn’t work in UE 4.11preview5! It is reported in bug reports already, so I hope it will be back in final 4.11
If you have questions, ask anytime. Have fun. Cheers.