Tried both. The Nyth is far better when a large number of buttons are required. The button placement is far more comfortable and intuitive. The buttons on the SS are all over the place and is takes a lot of mental and physical effort to have you fingers shooting off in all different directions. On the Nyth the buttons are nice and ordered, making them instantly learnable, and despite what steelseries claim about this design being outdated they do not feel at all akward. Also the modifier is super easy to press which extends it's functionality.
The SS is not a bad mouse. It feels absolutely great in the hand and the mouse buttons are nice and clicky. I'd consider it to be an excellent fps/hybrid/moba mouse but when a large number of buttons are required the Nyth is the clear choice. Nyth also has a far superior scroll wheel... lovely and clicky.