He's still not a first rounder in mock drafts. I sincerely think he should bet on himself and stay another year (or even two). His skill level will have to be truly elite and his athleticism will have to improve to make it in the NBA beyond the rookie contract. He's not someone who will be drafted for upside.
It's always hard to argue against someone like Harkless entering early and getting drafted in the lottery (or just outside of it). But if he stayed one more year, he's a top five pick and a lot more polished. Who knows what type of NBA player he'd be now.