Final verdict on SMN 90: It's fine.
I did the 90 solo duty on SMN and boy let me tell you (spoiler hidden)
Trading blow for blow with Zenos as a SMN was really really satisfying. He uses Tidal Wave? Fine, I'll use Mountain Buster. And you're not the only one that can Akh Morn - he did too, and at the same time I did! Super duper fun.