Very impressive work! Feels like I'm playing BG2 now I tested it out in a few areas. I like how they won't agree to stay in the Cloakwood mines (Could be a problem for a player who doesn't pay attention, or just for the sake of getting the char. out of there to be replaced by a new NPC). Does Yes get killed if you leave him there?
I noticed Imoen goes to the 2nd floor of the FIA. Might be handy to mention where abouts they are going if you're going to use both floors, but that's just my gamer laziness talking. I thought I lost her for a minute
One other thing...
I'm not sure if you intended it to be the case, but I noticed that Viconia (being unhappy with my 18 reputation) exhibits her normal behavior and disappears (I'm believe she vanishes from the game, no?). I could understand her not wanting to stick around for your party if you have a high rep., but personally I think she should at least go somewhere.
Hmm, really, the option to drop an npc will be left available on nearly 2/3 of the areas. And the areas I marked as 'dangerous' usually have an exit to the 'safe' ones, where the npc could be dropped. It is not like I am trying to make the player's life difficult - just adding another role-playing aspect.
Worry not - this area is left 'droppable'. But I think that your npc should have reasonable doubts about being left on the Polar Isle or in the mine about to be flooded.
And there is never a danger of npc running away with your items - you can always ask them to stay using dialog option - strip them off the valuable items and then release - either to an inn or say farewell - this is basically for roleplaying evil characters.
Once again - it is an optional component, and it aims to both enhance the roleplaying aspect ( by making npc's more 'intelligent', if you will) and by giving the player the ability to easier rotate npcs in the party.
PC has 4 choices always after their npc refuses to stay in the danger zone:
1. Ask npc to stay with the group.
2. Send them to Baldurs Gate area inn. ( after chapter 4)
3. Send them to Sword Coast general area inn.
4. Dismiss forever.
I think it is fair enough.
By the way - I just finished writing and coding this component for all BG1 npc's (yikes! ) If you are interested - in the Work room the new download is posted. All npcs now have custom lines - with small variations.