Note8 user here, actually.
And no.
Main reason is this. There's very little in the S9+ that would justify the upgrade, and if history is any indication, the Note9 will be the same.
I am very sure they will be great phones. But we live in an era where new generation phones are about iterative evolution, not revolution. Unless you have JOD or the like, I just can't see why I should upgrade so soon, especially when my Note8 is not even 6 months old and has been performing extremely well to this day, actually, better than I expected.