Originally posted by: darXoul
I'm a "pro gamer" (mainly Q3 CPMA) and I can tell you that if you're getting a new mouse, get the MX518. It's really flawless. To be honest, the MX510 is not really inferior since the sheer precision doesn't really improve going from 800 to 1600 dpi. Still, if you get your sensitivity settings right, there might be a subtle difference.
As for G5, except for the rougher surface which is IMO better, I don't like it too much. The scroll wheel is just plain bad compared to MX's, it lacks one thumb button which I got used to, plus the laser sensor is more picky in terms of mousepads. The difference between 1600 and 2000 dpi in real world use (including games) is purely academic anyway.