My thought was, to address the progression through talent trees (there is, to be honest, a CRAZY number of talent trees!), is to do it like a movie. Play for a little, get a little better, then have a hard break and dump about 150xp on everyone. This would allow everyone to experience the game at different power tiers while still adhering to the 10 or less campaign postulated above by Ralph Mazza (a good guess, in my estimation). Do it like the breaks between the movies where Luke goes from fodder to badass between Empire and Jedi.