I absolutely want feedback 
for The roughness you are right, i forgot to adjust it, i was using an older release of UE, and switching to 4.6 has changed some materiale settings. The grass i used is already shared ob YouTube by a guy who named it “advanced grass UE4”
The Garden of Eden in Unreal Engine 4 - Darker Ve…: http://youtu.be/AFvdK6ZPBN0
There is The download link
Soon i’ll upload the progress on this work