Tested it out for butcher seems to be work. The X,Y,Z's aren't set and spaced apart so you get duplicates of the same NPC like right on top of each other difficult to notice and detect in game unless you like stun/root/bash the npc or kill one.
I plan to space them though I could see situational instances where you might want to put them to trick players thinking it was a single pull when in reality it was multiple spawns! Anyway should look pretty good once the coordinates are fleshed out when I have time to do so. I'm pretty excited about this spawn density stuff and have a lot of clever ideas on ways to utilize it to give EQ a lot of variety.
Example take night and day spawn cycles like Kithicor uses and apply that philosophy to mob density for a zone day time you have 1 zone night time it bumps up to 2 or it could scale up at 1PM game time for a given time length by X number of mobs! Suddenly that single rat spawn is a full camp of plague rats on it's next spawn cycle ready to eat you!
(NPC SHOUTS YOU DIRTY RAT!) I digging the custom potential of this and increased variation and challenges it can provided.