Zau did just fine with ECL 2 working properly.
I won't really go into an in depth discussion about darkness, as I do not really think it made much of a difference in the success or failings of specific drow PC's we've had.
The reason drow can't survive anymore is there no faction to really protect them. (Which is how it probably should be in Sanctuary, given the history of the VTG, and Sewer Drow have had in the city.)
At any rate, as this thread is still going on, I will go through a more detailed reasoning as to why I'm strictly against this. As I posted before in my previous response, drow are not born as destroyers of men. Many are commoners, and weak, etc.
What makes drow truly terrifying though, is the place they are raised in. Traensyr for example, is hardly a safe place. It is a ruthless city of rival houses that are nearly constantly at war. Drow are plotting, scheming, killing, culling, and training continually. Academies exist that have some of the greatest instructors in the Underdark. The soldiers that enter these academies, if they survive that is, yes, will come out at level 10 with generally +2 gear afforded to them by their trainers and sponsored Houses.
The same is more or less true of priests, assassins, and wizards.
Exiles, though, have none of this, nor should they be feared. They are removed from the society that makes them every bit as terrifying as you find the NPC's, and in general, should reflect that.
That said, having suffered through a few drow PC's, I am genuinely impressed with the success some have accomplished.