I ran a 25.4 sphere last night just for kicks.
Even with high-density support layers and a .1mm layer, the bottom third of the ball is distorted. I suspect it's more thermal that support issues. I'm thinking that if you ran a batch of 10 at a time things might turn out better since the base material would cool more before trying to support the next layer. I could be totally wrong, but if I wanted to print nicer balls in one piece, that's what I'd try next.
Personally, I'm not interested enough in the challenge to print off 10 balls.
If you really want nice, smooth spheres top and bottom, JimC's advice will get you there - print halves and glue them together.