I have found myself in a somewhat unusual position with regards to Anomen in my current BG2 party. I'm still in chapter 2, thanks to already having Imoen back in the party, so I've been cycling through NPCs to see which one the party should take to Spellhold.
Rasaad opted to stay at the temple, Mazzy is tending to her sister, Jan is still in jail, Viconia is going full emo in the graveyard, Cernd is STILL full emo in the druid grove, etc. Next in the list? Anomen. I figured I would help him get through his trials to become a proper night, then move on.
Except that, while he turned out to be annoying as I remembered, he was also incredibly useful enough to make up for it. The party is already around level 13, so his turn undead is powerful. During the cult of the unseeing eye, he was able to clear the field just walking around invisibly. That whole battle in the makeshift tent thing came down to four enemies - all the others chunked as soon as he walked up.
Also, given his history, I gave him the dark seed of guilt from ISNF. That turned him into a powerhouse. With another item, the elephant figurine, he took on a priest and an absolutely nuts merc, in the north forest. Sure, he was beaten up by the end, but he saved the rest of the party in the process. I might actually do the unthinkable and have the party take him to Spellhold. Yes, he's a pompous ass, but wow.
Right now, he's chilling at De'Arnise keep, but unlike other party members who have left, he still has his gear. I'm training Neera in the ways of magic to do her quest, and get a certain item in Athkatla. However, I don't see her staying in the party all that terribly long.