I think it would be cool for Force users to have the option to use the other side's abilities if they are attuned to that side of the Force. For example, you play a Jedi class and you reached Dark V, then I think it would be awesome if you had the choice to use the Sith's abilities. Perhaps make it a requirement that you keep Dark/Light IV or above, if you drop they revert back to the dark/light defaults. Probably won't happen, but I think it would be cool.