Apparently the 'leaked' stats for the cultist is out and ftom this little thing we can see a few things that are of interest.
1) Cultist are fucken cheap! 100 pts for a 30-man squad guardsmen makes them even better than grots for sitting on objectives. I could see how people who want to load up on nice toys would take them. However you do get what you pay for. If there is some cheap elite chappie of some kind to make them hold their ground they would be quite an objective sitter.
2) Weapon options are quite subpar in a way as you either get the close combat version or the shooty version and get upgrades that are limited to said roles. If the shooty ones could get the grenade launchers they woukd not be bad but alas....
3) Icons are cheap. But what they do is anyone's guess now.
4) What is 'servants of chaos'? Is this a simple usr for chaos or is this some sort of tax on the cultists?