I'd rather keep Jerebko.
I think Crowder is a better SF than Joe Johnson is. Debatable between JJ and E.Turner. JJ gives you more shooting. Turner more defense, rebounding and slashing. Actually, that might be in Turner's favour as well.
I like Jerebko. Good utility player.
I don't want JJ. He has lost too much as a defender & rebounder. He is limited to being an iso-player on offense. Lost too much quickness. Not efficient enough at what he is good at. I don't think he'll add more to the team than what we currently have.