I've always thought Rogues to be the masters of deceptive combat. They strike whenever and wherever the enemy can't see them. A good enough rogue will never be seen; to this effect I think that making them immune to rampage and whirlwind is in order. You can't hit something you can't see, (maybe get a few blind strikes here and there, but maybe that's it) so you shouldn't be able to rampage it.
Back a while ago when Monk triple attack was nerfed, other classes got it nerfed too, so it was relatively balanced based on the numbers. Rogue DPS being low to begin with, this hurt them especially. Personally I think triple attack for Monks should be upped considerably, but that's another thread.
In summation, a tweak is in order I think. I've played CHASEUM (I refuse to refer to him as arraz, it's a crime), Droogie, and at least one other rogue in SoD, and their low DPS is relatively consistent throughout the tiers.