Overall, I find the G602 not as ergonomic as the MX510. The rearmost button in the bottom row of the side buttons is pressed accidentally easily if you lift the mouse. I have therefore not assigned a function.
The software from Logitech is currently poor. The latest version (9.x) does not recognize my mouse. An older version (8.5) does not automatically start up when Windows starts.
Conclusion
Logitech I expected better, but really bad the mouse is not. In addition, the competitors seem to focus on design rather than ergonomics and durability. The G602 seems to be currently the one-eyed man among the (almost) blind.