I don't see a problem with disabling an AI mod mid-campaign. Just unsubscribing from it and running with Better Advent instead should cause no problems.

Of course, the other way around would be another story. Once you run Better Advent on your campaign, disabling it can cause problems. Not because of the AI, but because of the enemies and missions on your map that may already have spawned with them.

Ok I did unsubscribe to the AI mod I had, then subscribed to your mod, but as I was expecting it to happen I now have the "missing mod" warning when I try to load my save (as usual).

Is it some ini file check the game does somewhere I can edit ? or is it in the save file itself ? :'(

I loaded my save and it looks ok though, the game didn't crash yet :)

Oh, that missing mod warning is always there when you disable a mod. Any mod, even if it's just a voice pack or a hat or whatever.

If your save works, you can continue - it's just a warning.