Right got the new G9x and got a mixed feelings about this.
Pros-
Shape - Feels comfortable with both large and small grips. Still not sure which one I prefer (grip wise). Although not as good as MX518 in my current opinion, however hopefully i will get use to it.
Accuracy - very very smooth, probably more precise in the movements than the MX518,
Movement - Both 518 and G9x are good and glide across my Razer hard steel mat effortless, Edge this to G9x as the added weights does make a difference, if like me u like a heavier mouse. If you dont not a problem you can adjust the weights to suit
Profiles - are quite good but not something i can imagine i would use a lot.
DPI - on the fly Adjustable DPI, again not really something i currently use but that could change i suppose.
Cons
I really only have one issue with this mouse and when i read this on the net i'd never imagine it would literally be this bad.
Middle Mouse Button - argh it so hard to press compared to other mouses. You literally have to force it a good bit to register the click, At first i thought wtf, is there even a middle button.??
There is also a tilt left and right button functions on the same button as well. hmmm not sure yet but like i say it early stages. Not really happy about it but i will see if i get use to it or not.
Overall fairly happy with it. Will perceiver and see what happens in the long run.