I just put mine up on Ebay solely due to it's weight. But I have noticed I pick my mouse up a lot as I use it. This is something I never noticed until I started using the G602. One of the issues is that most of the weight is at the palm end of the mouse (thats where the batteries reside), and since my fingers grip the button end of the mouse to lift it, they were having a difficult time because of the weight distribution (the front would lift easy but the back would drop, pulling it from my hand a bit). It's not a super huge difference from front to back but I could notice it.
I noticed after a week when I plugged my G7 back in to start using it again, that the weight is very uniform along the entire mouse, making it easier to lift. Strangely, my G7 isn't all that much lighter that the G602, the weight distribution made a big difference.
Also It does seem that the groove that my pinky fits in on the G7 is a bit deeper, again, allowing me to lift it easier.
I can't say anything about all of the other specifics of the mouse except for one thing. I don't play FPS games much at all, and in the games I do play, I left the mouse in endurance mode and it operated just fine. (thats the mode that uses less energy from the batteries) So there is one positive.
I liked it a lot other than the weight issues, but I need to go back to a lighter mouse.