WARNING There are two models (I do not mean the color) of the mouse, Version 2012 and Version 2013. The 2012 version has an EXTREMELY annoying bug which randomly jumping cursor over an axis. This bug occurs for users who use the profiles stored in the mouse memory (does not occur if you install LGS AND use a profile stored on your computer). In addition, this bug is not correctable via an update, Logitech has just released a 2013 version (without any indication on the packaging) with the bug fixed and by adding the ability to update the mouse firmware .
People receiving the 2012 version are harmed because their mice have uncorrectable problem and, in addition, can not benefit from future updates!
Having purchased the mouse in February 2014, I received a 2012 version ...
Otherwise, this is an excellent mouse (the best?) For MMO players. The number of keys available on the go is a real advantage.
For fast FPS, this is worse because the mouse is large and unfortunately difficult to keep on hand during rapid movements.