Is there any benefit to go beyond level 4? If so what is it.
More average points earned per day.
You get a slightly bigger charge doing belts each time you gain a level in manu although the cost in CPs for each charge goes up each level also
It's the only career with less than 3-4 skills at lvl 10, I'm guessing Zen isn't done creating some for it, just hasn't figured out what yet or the game isn't ready for that/those specials yet.
keep leveling those careers, more to come in near future I bet... Might as well, get up there now, so you can use those new features instead of having to build up to them...
I dunno what pts for manu are like but for my career I can earn up to 28pts in OT and 19 pts in reg hrs.