Besides the shape how else is the xornet superior to the ss.
Xornet is plug and play, no drivers needed, last time I checked SS used some horrible driver for their lower end mice. They've also been known to use ****ty sensors, at least in the early Kinzu models. I'm not sure what they put in the blops2 one, but even if the sensor is as good as the Xornet one, there is no reason to pay extra for it when the Xornet is cheaper.
Basically; the Xornet is good, it's a safe bet. The SS mouse costs more and will at best be equal to the Xornet, not worth it at all unless you really want that shape, in which case this thread would be pointless.