Everything works unless I reload my save.

[EPDGaffney]

Thanks for all that. I'm not really well versed in the differences between the two and frankly used to think that .esm files were mostly only necessary for modders because of bugs like the mismatched bodies and heads (or at least, I think that's an accident and therefore a bug, but maybe that was the intentional standard by the developer), and now I see there's this navmesh stuff, so I'm starting to think they're fairly different types of file, and I'm going to need to know just how different before I decided what to do.

 

To me, the major advantage of using an .esp is freedom of load order placement (and ease of editing for me). However, I think I've effectively avoided all potential conflicts by using scripts instead of record edits, so I may be able to proceed with just the .esm file. I've even gone to the length of making custom armours that reflect the correct race of some NPCs in order to avoid using an .esm.

 

Another really odd/interesting thing I discovered was that when using an .esp file, one of my NPCs was getting duplicates of some items in his inventory, and they were completely bugged. They would display twice, and if I took one off of him, both would be removed and I would receive only the one copy that was supposed to be there. This was one levelled list item, the vanilla Combat Helmet; and one custom item, a knife, that is added OnDeath. It was the same every time I tested, for months, and when I tried my mod as a master file just now, this problem was not present.