Hello there!!!
This is my first time uploading artwork here and I did this mech for a class that I'm taking about Zbrush... (ZBrush 4R7: Everything you wanted to know...with a side of mech)
Basically I used the Zmodeler brush (new in Zbrush 4R7) for the entire mech and then Blender for the UV mapping. After the "fun" times doing UV's I did send the mesh back Zbrush for details and polypaint using spotlight (that was really fun and natural to be honest). Once I finished the detail part I send a higher polygon version of that mech to Keyshot in order to get the final render.
Reason why I spend time doing the UV in blender is because I want to send that mech to Unreal Engine... Was not really needed for the Zbrush/Keyshot part
Thank you very much