I have the Sidewinder x8 as well, and this is hands down the best mouse I have ever owned. I honestly live in fear for the day that it dies on me. It is the only mouse where the side buttons are up and down--PERFECTION. The little magnetic cable to charge is a smart addition, letting me remove/plug back in with a single hand. I love this mouse, and as interesting as the specs are for the Gigabyte one are.... there is just too much that I would lose.
love my X8 also. only way it could get any better is if they added a 3rd top side finger button. the two vertical thumb buttons plus the 3rd thumb button fixed infront are a priceless set up. switched out the batter for a phillips 2700mha rechargeable and it goes all week with out needing a recharge for an rpg like diablo or rts like supreme commander there aren't any more decent fps games i have tried LAN'ing this with, but with netflix destroying response times across the globe for online playing i can't tell if there is any 'lag' for bf3 due to the absolute destruction of online gaming netflix has reeked upon the planet.