I've gotten about 200 surveys split between wood, cloth, and ore now. 2 of the 3 cloth surveys and 1 of the 3 woodworker surveys are located in Lower Craglorn. I have never received a nirncrux from any survey located there.
I don't think they stated anywhere that the survey must be in Upper to receive nirncrux, but I think that's a bit ridiculous that nirncrux doesn't drop from Lower surveys.
Hypothetically if someone only did surveys on Clothing, and someone only did them on Blacksmithing, that blacksmith would overall obtain much more nirncrux than that clothier. It's unfair to make limit each craft in the chance of getting a survey which can possibly yield a nirncrux. Wood, Cloth, and Ore should be equal in that regard.
Because surveys are instanced to the player individually, and also labelled as "Rich", "Lush", or "Pristine", I don't think it would be too difficult to incorporate nirncrux drops to those Lower Craglorn survey locations.
Edited by Fat_Cat45 on 22 March 2015 21:19