although it did mean that every aware enemy could predictably try to mob you without just emptying out the entire rest of the map.
Be very clear. An entity is a single enemy. Don't fucking say mob afterwards or I'm going to be confused as heck.
This is good. Using pathfinding is important because for the longest time we didn't have intelligent enough rules to seek and move through environments as intelligently as humans, right?? Remember how hard it was for us to build robots that could walk up stairs - or detect the floors vs the walls so we could have vacuum cleaner robots..
SO, using global AI keeps the game ahead of reality. The sounds and what not are gameplay.
You did not do anything new for the stealth game genre, but now you can.
Local AI is realistic like reality, Global AI is outside of your walls.
So think about what you want the players to feel. What's their angle?
Build from that.