Just to add an additional comment; I don't believe it's even possible to use the dark side and the "force" (I refuse to call it the light.) as some balance. Corrupting the force to your wim's is simply evil and using the dark side will corrupt someone rapidly, even if done for fair reasons. Just the Bendu suggests that knowing about those corruption powers isn't necessarily evil in itself, understanding is the first step on the path to enlightenment and none can ascend that path with pure ignorance alone as they would be unable to recognise when they are being manipulated. So that they know what to avoid and what is considered acceptable.
Just putting that out there; largely because I believe Grey Jedi are a crock of something unpleasent, and have almost always been identified as a secret darksider or as a term of slander (Qui-Gon). You either are a Jedi or not, or a sith or not. If you are not, then you are a force user or belong to another faith.