[triqui]

As already stated, Berserker give you a total net of -2 fatigue per turn, which is not exactly the same as encumbrance 2.

That said, the overall effect of Berserker is positive. It lowers defense, but raises protection, which offset it (+2 protection is better than +2 defense). It gives you attack and strength, which increase overall offensive ability. Plus being unbreakable is very sexy