I guess the motors are same apart from s2r1000 has oxygen sensor and it has a cat underneath. I imagine the m1000 is less restricted by not having any of it.
As for looks i love the sss one of the reasons i got my s4r its just so sexy!!
Easy chain adjustment and allignment and ease wheel changes to.
Dont get white wheels lol pain to clean!
I say go s2r1000