I'm going to preface the following discussion with these words: This is not a debate over what is canon or not, but discussion on how the following points could effect how the Force is used or otherwise portrayed within the Tabletop RPG. That being said...
I have always found it interesting how the Jedi perceive themselves within the Star Wars Universe as the "defenders of the Republic and the innocent". And yet, when it really mattered, the Jedi were wholly content with just sitting on their hands and knees as the Mandalorians pillaged their way to Coruscant even going so far as to seemingly refuse to allow the Republic to fight back on its own, even without the Jedi. And yet when their apathy and indifference to the Republic's plight was questioned, Revan and Malek were cast out and declared Sith for doing the very thing the Jedi consider their role: defending the innocent and the Republic.
(Interesting side note: If absolute obedience to the Council was their highest mandate, then technically speaking Obi-wan should have been cast out for threatening Yoda to go against the council's refusal to train Anakin, but they didn't).
At this point I believe (prior to TOR's retconning of Revan's motives) Revan realized a fundamental truth, that the Jedi only acted when it served their own interests and not those of the billions of people they were sworn to protect. Thus he set out both to destroy the Sith and free the Republic from the apathetic rule of the Jedi. This goal is further backed by the fact that even Master Yoda and the council were once again openly against the Republic forming an army to defend itself against the military and economic assault of the Separatists, even after discovering Sith involvement and even more so after the Separatists had already begun their attacks. Even then the Jedi clung to their self-indulgent image of themselves while openly refusing (until they were literally forced) to defend the Republic.
Which brings me now to another point about the Jedi: their portrayal of users of the Dark Side. The Jedi wont hesitate a second to almost brag how all Sith are hate-ravaged boogymen that want to devour your children, while they are serene and "one with the Force". And yes, while there are more than enough examples to back up this stereotype, the very aspect of stereotyping seems beneath the Jedi. If you go solely on how they believe themselves to be. Furthermore they clearly state that force powers are either inherently good or evil, and how such power is used has nothing to do with anything. If this were true, there would be no Grey Jedi. It would be an absolute impossibility. Yet you have individuals like Revan and Starkiller who were masters of both the light and the dark side. Heck, even the Bendu would not exist because it would either have to be good, or evil but could not be both.
Take for example the Jedi's Force Pull. There is absolutely no way that power could be evil right? I mean, it's not like someone could use it to pull a person off a balcony to kill him/her and make it look like a suicide in the process. Just like there is no way someone could use Force Lightning to start a broken down speeder for some poor sod stuck out in the Dune Sea.
And now we get to the individual who just throws all the Jedi's doctrines out the window: Lana Beniko, a character from The Old Republic MMO. During your first few interactions with the character, she comes off as well mannered and polite. True she can be curt and calculating but never aggressive, callous, or conniving. Yet despite her bio even openly stating that many mistake her for a Jedi, she is, in fact, an extremely talented Sith Lord. What makes her even more intriguing when analyzing her from the aspect of how the Jedi love to portray all Dark Side practitioners, is the fact that on several occasions states "May the Force be with you." or "May the Force serve you well." Statements that are certainly more appropriate for a Jedi than a Sith.
Furthermore, after forming a shaky truce with the Republic, Lana heads an operation that sees a Republic special agent purposely captured (without his knowledge) knowing that he would be capable of gathering intel from the inside. The event causes seemingly irreparable damage to their partnership. Yet while a Sith shouldn't care one bit about "sacrificing a pawn" or somesuch, she takes his distrust and anger towards her extremely personally. Confiding in you, the player, she admits that while it made sound strategic sense, she not only regrets using the Republic agent (an enemy agent) as a pawn and is conflicted in her wish to openly, and sincerely, apologize to him for her breach of his trust. Yet at the same time, she realizes that he is, ultimately, and enemy and does not want to show him weakness (remorse or otherwise the existence of a conscience). And yet despite a rather amiable nature and a vast knowledge of the Force she can fight and hurl Dark Side powers like the best of them. Yet she shows none of the blood-craving malice (Darth Maul) or the physical manifestations (such as Darth Sidious) that the Jedi state is inherent in being a user of the Dark Side.
Thus, there are only two possibilities:
1) She is somehow more powerful than even Sidious, which I don't believe for one second. The only evidence of this would be the fact that she shows none of the physical corruption (outside of her eyes) while most (if not all) other Sith Lords do one way or another. Even so, the idea is too absurd to take seriously in any respect.
OR
2) She is actually a Grey Jedi in the same vein as Revan or Starkiller and only happens to be serving the Empire (not that the Jedi would have accepted her anyways).
The second choice has one other interesting implication. If Lana Beniko is actually a Grey Jedi, then that would mean that the title of "Sith" is simply a label the Jedi place on someone who does not agree with their world view or doctrine much in the same manner as the Pilgrims would put a scarlet letter on an adulterous woman to disgrace and shame her in the eyes of the world. This would also mean that the Force is not inherantly good or evil (this idea backed up by the existence of the Grey Jedi), but it is all in how each individual chooses to use those powers.
Thus the question is: If someone can be a practitioner of the Dark Side and yet not be corrupt, treacherous, psychotically violent, and anger-driven, what would that mean for the universe and force practitioners? How would it effect the rules on the usage of Force Powers within the campaign, and how could such a character be used within a campaign to mix things up a bit?