get which ever 1 is cheaper. they are as good as each other in my opinion. the g9x loses out slightly due to lower dpi which in turn means more prediction but to be honest the g9x was and is an excellent mouse. the prediction i mention was never really an issue with it so its not really relivant in any way other than its there because of the lower dpi. but because both mice have higher than needed dpi anyway its not really an issue but more of a way to differentiate 2 very good mice... honestly i wish that was the only issue with most other mice but with these 2 its about all you can mention and have any wiggle room for an opinion... that is if price isnt an issue.
there both great mice so try em both and send the 1 you find least comfy back. as you wont be disappointed with either.