Do new npcs upset xp balance

Haven't played yet due to bugs but I was curious how much xp was just added into the game with the new characters? If I use them in a full party am I likely to be in TOB levels without also doing watchers keep in SOA? I do not really meta game too much so I make the choices I want not the most rewarding choices.

Also I have SCS and it put duergar in replacement of goblins in Irenicus dungeon. Does it do a lot of switching enemies that it will add a notable amount of xp to my total by the end?