Hm, except it doesn't seem to be working quite right? I have my hidden sig settings as:
Enable: Yes
Hidden Sig Usergroups: 1, 2, 3, 4, 8
Hidden Sig Users:
Minimum Posts: 0
Opening Spoiler Code: (unedited from default)
Closing Spoiler Code: (unedited from default)
Hide for User? No
Prevent Sigs Completely? Yes
I can still see sigs when logged in as a regular registered user (usergroup 2).
EDIT 1 - If I set it to have a minimum post threshold before user can see sigs, I can only see the Administrator's signature, all others are hidden.
EDIT 2 - If I leave the post count limit to 0, I can see all user sigs.