I had a MX 518 before that I am very happy with (until the right button started sticking).
This G9 seems to be a better mouse but it takes Kanke some time to get used to. The friction is very low, which feels a little strange but the term certainly is a big plus. The precision feels passable after you fooling around and tried different speeds.
G9 is a pretty little mouse which is bad for me personally. I would have preferred one of the MX500 Series size. (Perhaps MX518 feels clumsy after a period omvänjning ...)
Something that is really awful of Logitech's writing that you can buy new skins even though it is not produced alternative shell (and if it ever comes, it will probably only be with new colors). Lousy driving with false advertising! When I bought the mouse, I thought I might well change the cover if it was too small but it is thus not possible (both shells provided are small).
I'm experiencing thumb keys as little unclear. When Browsing is fine but if you want to use them in fast games, it is easy to miss a keystroke that no one really knows their contours.
Trvligt with tilt wheel. Even the mouse wheel (like all other buttons) side presses can bind a little anything (keyboard keystrokes, macros, etc., etc.. In games, I use them in place of the buttons that I miss from the MX518's top and the windows have I use them for sidscrollning.
The weights feels superfluous. I think that the mouse weighs enough without a single folded tuck.
Quick Scroll with No freed wheel also feels a bit unnecessary. I usually do not have the need to scroll very quickly through hundreds of pages. Maybe I should start using it occasionally if it had been a little less circumstances to change to the usual incremental scrolling (button switch located on the bottom of the mouse).
Overall, I'm satisfied with the product, although I would have liked that they retained the position of the buttons on the mouse's top side and a few other minor problems.