HA HA! I have done it! I have defeated Sarevok and won the battle with the Tales of the Sword Coast add-on. Of course this may not mean much to others, but since I've never played with the TotSC addition, it was quite the game. From Olgoths Beard, battling on the Ice Island, and raiding the entire top half of Durlag's Tower at only level 5 and 4. I never got to the bottom half, and honestly I figured I didn't want to push my luck. Heh. Had to vent off a bit...
Anyhow, I am rather filled with high moral, and am off to press on in Baldur's Gate II.

"THERE IS VICTORY ENOUGH FOR ALL!" -Minsc

You really need to do the bottem half to get all the good stuff down there.