Thanks for the updates Chris! And definitely understand the way you are approaching it. The realism is definitely overkill for my project, but I just want to do an experiment to push to CGI realism as fast as possible in Cycles by using bought assets 
On the shaders vs textures point you make: I think setting the shaders up so they are easy to plug maps into will be the most important part, especially if you are pushing the Universal Human project further. For example tools like MetaHuman will soon change our workflow into scan/node based portraits.
I think the most logical approach would be a one-size-fits-all shader that will take maps from scans and UE4 metahuman exports, allowing for realistic previz in Cycles. I have another project in mind that uses the MetaHuman-first workflow. If I could take this, go to Zbrush to sculpt the finer details of my concept art, and then steal/hack maps together to go straight to CGI realism I will be a very happy camper. The left-side image took 15mins to mix together, which is pretty crazy.
In the meantime I have set up a thread for The Divided States project with some images on how that is going