So I recently got my copy of Destiny, and this whole time I have my fantasies of playing bladedancer. I really love the concept. Well anyways I know that reaching lv15 unlocks the second subclass for lv1 on all new characters too. So my question is: does a second subclass level up quickly post lv15? Or is it better to start over and level up that subclass from lv1 and get the most out of it?