Just a thought, but its my opinion that there are three types of Sith
Good categories. However, amongst uber-focused Sith I missing Darth Bane, who is considered to be a Sith'ari.
Siths consumed by the Dark Side are just pawns to manipulate and kill, like Tyranus' bunch of Sith pets. Better self-control means tougher Sith and better chance to achieve the title of the Dark Lord. Always.