G9/G9x guy here. I have a RAT7 infection. Bought it in an attempt to change from claw grip to palming for fps/work. I ended up with a hybrid finger grip... Anyway I have it and I'd totally be willing to get rid of it if it wasn't for that handy dandy sniper button. Hate the mouse otherwise. I caved and let my job buy me an MX performance, and I haven't come close to switching from it, despite wireless. No wrist/palm pain for fps or D3, no lag, feature filled, and reliable. The Rat7's got that Philips twin eye sensor that renders either the x or y axis useless until the mouse is lifted and placed back down, and it happened to me about once a day. The sniper button is a feature I miss, but that's about it for me.
Senseis are cool, but I kept going back to the G9. Are you looking for a Rat7 for fps?
TL;DR
I second the rat7's faulty sensor, and am happy with the performance mx after finally switching from a g9.