I have the Gigabyte M6800, and have had it for a little over 2 years and haven't had any problems with it. Works just fine, I would highly recommend it for a budget gaming mouse. Its a pretty basic mouse, but it does feel comfortable and has very good dpi between the two settings. If I had any complaints about it, it would be that is a little on the light side. I would maybe preferred a little more weight to it, but definitely not a glaring defect. I also really like the finish on the mouse, as I am a heavy computer user and tend to "wear" out mice fairly quickly. I have a WoW steelseries mouse that I cannot even stand to have on my desk because the finish on it wore out so badly after a few months, the thing just looks horrible now.
Over all, I would say for the price, it would be hard to beat the M6800.