I use to use the G500. I think I wore it out, it was great though now I use the Razor Naga. I know its a MMO mouse but it is great for FPS games too. Takes some time to get used to, its geared more for smaller to medium hands. The 12 thumb buttons are great for sticky situations. I tried the Lachesis for a while but it was just too large for me. The Logitech G110 Rocks, you will love it. Rocketfish pads seem to work great for me.
"In the absence of orders, go find something and kill it."
- Field Marshal Erwin Rommel