I don't know about in-game writing, but the story arc that has stuck with me the most is the Terra Conspiracy from Ginger Yates in Founders. At the finish of the arc I always feel so sad for what happens, and it really makes me hate Hamidon.
I followed the directions for the vidiotmaps but I ran into a problem. I could not find an existing data directory in the Contents/Resources/transgaming/c_drive/coh folder. When I try to place the data folder from the install there, the application will not start.