Thanks. This will come in handy.
However, moving this script to serverside I've noticed it takes quite a bit of CPU usage (at least serverside, it does).
Also, you may want to add some sort of offset option, for cases like a normal player character type NPC where the top of the head doesn't need to be counted as a blocking area.
Additionally,
this paper might be interesting to you! It's basically on how to efficiently find paths with variable size entities; it also has a lot on dealing with multiple types of terrain where entities have certain types of terrain they can clear but that's probably not that important (unless you want it to be!).