Well, in addition to changing to the job, you get a fixed bonus besides the points per level like I explained earlier. (Let's say, x class gets +5 Str)
You lose out on this fixed bonus for 2-8 battles. Early on in the game, 5 str would make a huge difference, so you may struggle a bit for said 2-8 battles. But later on in the game when you have like, 50 Str, it's not that noticable. =P