I was in the same boat as you, coming from a Logitech g9 which I eventually started to find made my hand lean to the right and was also way too heavy.
The Xai isn't really worth the price, if you like the sensor and the form factor, you might as well just get the Kinzu.
As for me, I ended up going with the Razer Abyssus, I got it for $35 CAD. It's symmetric so no more leaning, lightest mouse I've ever used, no tracking/accel issues that I've been able to notice. The only issue with it is that it is VERY picky with what mouse pad you use it on, I was using a qck+ and the tracking was absolutely terrible, it was jittering all over the place. Switching to the Razer Goliathus Speed solved everything though.