I like Khorothis's first version of the list, with the cultists. You really need at least 1-2 cheap objective grabbing units when playing 6th edition. At 1500 points I wouldn't use less than 3 troop choices, and 4 is definitely better.
Only other thing I can add is it might be nice to give the cultists a flamer. It really helps against hordes.
The first casualty of war is neither innocence nor truth.
The first casualty of war is always subtlety.