Looks good and similar to what I am trying to build in a an Intellijel 104 HP case. May want to check out the Befaco Hexmix and Hexpander as an option for a mixer - it may save you some HP.

Just picked up a Metron myself to start my rack but not sure about the workflow of the Voltera - may at least get one. Per your vids definitely getting a Mimetic Digitalis and also a Arpitecht. As chrisusu asked why no Mimetic in your case?

Was also thinking about the WMD percussion modules but its just to much space and I really like The Division Department 01/IV and will just deal with it being outside the rack. BTW just picked up a Launchkey Mini and love the arp functions!