Your trip through the underdark is going to look like a picnic i think.
Switching jan for haer isn't a serieus option i think, like hordfactor says, he needs the thieving skills, dunno for sure but i think jan is better with magic compared to the bard, and he doesn't need haer at all in the frontline, since he has 2 berserkers and viconia.
Btw did you get that medium shield that gives you extra (about 20% i think) magic protection? It's great for viconia. Either you get it from Madulf or in the Unseeing eye quest, think the first. Memory not so good anymore
Another thing i'm not sure about: if you would have dualwield korgan with some axe or warhammer AND the Crom Fayer of course and give yourself a shield and the celestial fury for example, you could have been stronger in the end. Not sure though. And I'm really nitpicking now
