I would want to kill the old characters
But seriously, I think that it would be cool to run into a couple of characters from BG2. I don't remember what happened to each of them after TOB, but any you do meet should be in a position of great power considering how strong you were at the end of TOB. Also, I agree that if they are used it should only be a couple of them for cameos. I hate the idea of being barraged by Npc's from an earlier game.