I started a IA game recently and i'm so far enjoying it. I've never tried IA before, but i have played vanilla BG2 extensively as well as SCS, Ascension and Tactics. I'm following Raven's recommended quest order. However, the time comes to make a tough decision. I'll be off for Spellhold soon and i'm certainly planning to pick up Imoen. Tbh: i can't imagine a game without Imoen, with her being such an integral part of the plot. Besides: i love sorcerers
My party consists of:

protagonist: sorcerer
custom made berserker
custom made multiclass fighter/thief
custom made ranger->cleric
Cernd
Valygar

Obviously, i need to drop someone from my party. The choice is between either Valygar or Cernd. In a vanilla game or Tactics i would prefer to keep Cernd, since he's quite a powerful spellcaster and spellcasters rule late game there. Besides, it never hurts to have an extra healer. However, the consensus on this forum seems to be melee is more useful than spellcasting in endgame IA. I'd appreciate any advice on this from veteran IA players.

Mohina

I would suggest that you keep Valygar. Auramasters are great spellcasters in the correct hands, but you will probably find that warrior HLAs become increasingly important later on as certain enemies are very hard to hit and most offensive spells would prove useless against them.

Also, I am not too certain that you should take Imoen since your protagonist is already a sorcerer... Nalia may be a better choice with her upgraded ring and her wider spell selection... but 2 sorcerers can indeed be very powerful if you choose the right spells.

Agree with LZJ. If you inted to get Imoen (Nalia is better choice imho since you have sorcerer protagonist), then keep Valygar. Alternatively you could skip Nalia/Imoen at this run and keep Cernd beside Valygar. Game will be a bit harder with only 1 arcane caster, but if you chose carefully, you can do it, and Auramaster can shine for a while. End SoA abd ToB will be harder imho with only 1 arcane caster.

Thanks for the advice. I'll take Valygar along for the ride then. He's pretty good in IA with his improved stats and there seem to be plenty of new (forged) items around for two rangers.
I did consider Nalia instead of Imoen and i can certainly see your reasons for preferring her to Imoen. I mainly chose Imoen for roleplaying reasons. My protagonist is lawful good and would never abandon a childhood friend in Spellhold. Hopefully, a wise spell selection will prevent any problems.
Another option would be to swap my f/t for Haer Dalis once i return from the Underdark. I haven't done the Planar Prison yet, but i certainly intend to do that once i return from the Underdark. Not entirely sure how much you actually need a thief in IA. Imoen has Knock, if i remember correctly and in the vanilla game most traps can be avoided/circumvented (mirror image, etc).
A blade gives both melee abilities (properly buffed) and additional spellcasting options. Only problem is that i find Haer Dalis almost as annoying as Anomen:P
Anyway: thanks for the advice again. I will go with Imoen and Valygar for now.