Happier than flying part 135, getting called to fly to an airport with no FBO in the middle of nowhere in the middle of the night, only getting 4 hard days off a month, and flying for an outfit with no standardization in flight training? Hell yes. The pay is a temporary adjustment, but I can live with it. Don't worry about studying anything before you start. If you get a break between indoc and systems, then use that time to lightly review systems and study memory items. If you already have a type rating, then this is really just a minor transition into a new airplane. The systems aren't difficult to understand, and you'll probably spend more time studying flows and callouts than anything else.