I have a Sith Sorcerer and a Consular Shadow. My biggest reasoning behind this was that throwing around lightning is really really fun, and the Lightning tree even gets a Ki Blast.
Project is one of my favorite abilities in the entire game. From what I can see the Sage doesn't really use project at all. Shadow does. I really liked the concept of mixing melee with kinetic force powers (as apposed to melee and lightning). So far Shadow Infiltration is playing exactly like I had hoped. Jumping from the shadows with heavy melee attacks, and then building up to unleash powerful force attacks.