Um, wireless mice are nearly always going to be heavier due to batteries/etc. My mx1000 is pretty heavy, but I've gotten use to it. Still I suspect I have a mild handicap because of it. Sometimes I'm tempted to get a wired mouse just for gaming.
The Mamba weighs less than the Logitech optical wired mouse I use at work. The thing feels light as a feather.
I'm not saying the Mamba is the perfect mouse or anything, but it weighs next to nothing.
KT