Your post said too many obvious things.
1) "It can't be OP" (Well obviously)
2) "I don't know how it will work with only 5 job skills" (Well, I guess SE will add it in 2.0 where they WILL be able to do thing to bypass that limitation.
3) " I'm open to suggestions on how SMN will work in our current battle system." (Well, you aren't a game developer, we can't actually suggest anything to you. We can discuss things with you.