In DragonQuest IX, what happens when you change your vocation?

In DragonQuest IX, what happens when you change your vocation? See, I dont like the minstrel (main character of the game) well its not that i dont like him, but i much prefer he does some other occupation, preferably a theif or ranger or the sort... but im a little hesitant as to changing his vocation cuz i know there are some setbacks. does anyone know what happens when you change the vocation?