Hey there, updating since I did end up buying those 2 extensions. They work well and I think my players will be happy with them, but I have what is either a bug report or something needing clarification:
It seems like any NPC's Inventory page does not calculate their Encumbrance values until they've been placed into an encounter map. Once placed into a map and the map-specific instance of that NPC token is checked, they have the expected values in their Encumbrance fields - check the screenshot. The Friendly Spider on the left is the sheet for the NPC opened from the NPCs list, while the Friendly Spider on the right is the token/sheet opened by double-clicking the spider's token on the map in the background.
Attachment 65845
So, is this a bug with the NPC sheet? I'd expect any NPC with a Strength score to have those fields auto-calculated.
Using an instance of the NPC on a map is OK for monsters, but for something like the party's pack animal or other shared inventory carried over long distances, we'll want to use the NPC from the NPC list rather than having to make a new token in every single map. (Sorry if I'm using FGU terminology about tokens and NPCs wrong - hopefully my meaning is clear.)