I’ve been playing with the 1.7.10 version of Ancient Warfare, and I’ve given up using NPCs for, well, pretty much anything.

The problem is that utility NPCs die off screen pretty regularly, even in a fully lit base. There’s no way to keep Endermen out of a base, and they can and will kill NPCs. Theoretically guard NPCs can help with this, but in practice they’re never in the right place at the right time. Priests can resurrect the dead NPCs later, but the inventory of the dead NPC is gone.

The worst case in couriers. Not only do they lose what they’re carrying, they lose their work order. A complex courier work order can take significant time and effort to create. After my food-prep courier lost his work order with 20+ stops, I decided to move on and use a pipe mod for item transport instead.

Equipping guard NPCs with decent armor is prohibitively expensive for the same reason. While they, at least, can defend themselves, they still die regularly off screen (probably due to Endermen) and lose all their equipment.