So I finished the master quest and I think all characters reached level 24. Below are a few observations,
may contain spoilers.
End game stats
Play time: 33 hours (I'm slow, I know I know)
Secrets: 115/120
Treasures: 7/7
Skulls: 5
Perel's note: all
Melee attacks: 1558
Ranged attacks: 1746
Unarmed Attacks: 1180
Spells cast: 1320
1. I gave most of the wisdom books and extras to my mage so he ended up with 50 in spellcraft, 14 in staff defense and 30-something in air and 40-something in ice. In the original game I used ice the most, but air does more damage so I found myself using it about evenly with ice in master quest. I think staff defense up to light armor was a good idea because it stopped the mage from dying easily (also gave him one of the tome's of health), and spellcraft 50 halves magic costs so it makes a huge difference. I'm not sure if it's a good idea to build up two elemental schools; I think the biggest advantage is that you get elemental protections for your party in those two schools, but I saw some guy on youtube with fire at 50 and he was dealing a lot more damage than my mage, except that his mage also died all the time. In terms of spells cast, it would have been higher but my mage ran out of juice easily until I got spellcraft up to 50 and also spells are inconvenient to click out in the midst of combat.
2. My minotaur rogue was the busiest member of the team until she ran out of ammo, but if you keep both a crossbow and regular bow ready at quick switch then you essentially double the ammo. But even then she ran out in fighter's challenge - I should have kept the slingshot as a tertiary weapon; the rocks weigh a crapload, but they don't stick to enemies like arrows so you can pick them up in the middle of the fight. As for enchanting ammo, it's not worth giving up auto-pickup imo. I know you can make your mage hold regular arrows or bolts, but then he can't hold a staff/orb/shield/bombs or a fire/lightning sword. My missile rogue reached 50 in missiles in the original game, so I put the rest of the points in dodge and later suited her up in Chitin (nice set bonus). That was much better than having her in plate/chain with massive hits to evasion.
The poison gems ammo for the slingshot was also a great addition towards the end of the game.
3. My unarmed combat rogue used to be faster and more accurate in the original game, but after my fighter got swords to 50 she was faster, and as accurate with Sword of Nex, and of course did more damage.
After she got full armor of valor she was essentially twice as fast as my fist fighter.
Still the fist fighter was a resilient bastard that would often outlast all the other members of the team because of high evasion (around 160) combined with immunity to fire/shock and high resistance to ice and poison. I decided to go with lurker armor, initially so that I could save the Chitin for my mage and missile rogue, but later also because the set bonus for lurker armor is too good not to use:
invisibility for your full party, although the invisibility icon only shows up on the wearer of the lurker set.
Of course I had to give up my pit fighter gloves (the only weapon for unarmed fighter) so that's why I suspect a rogue specializing in daggers, dodge and assassination might be better. Dunno. The reason he's lagging in unarmed attacks performed, probably has to do more with how I fight than his usefulness. I like to attack with both front row guys one right after the other before moving away or going to missiles/spells, and I do it so quickly that I don't stop to see if the first character's hit (sword fighter in this case) kills the enemy.
4. My fighter was awesome. Armors to 16 first to wear heavy, then swords to 50, and the rest of the points I spread pretty evenly between athletics and armors just to keep getting strength, health, protection and other bonuses. Towards the end she was too fast for me to take advantage of her properly during the flow of combat, so I gave her Dismantler instead of Sword of Nex and a bracelet that increased attack power but slowed the cool down. That way she was closer to my fist fighter (who had the bracelet to quicken cool down) so I could attack with them in unison.