I am having to use X-Mouse and the driver and X-Mouse crashes on my laptop for some reason. Basically you can't remap mouse up and down to anything with the supplied driver software. You also can't remap the mouse DPI button or the mode button. I have not figgured out how to remap the second and 3rd modes so that they have different DPIs and different button assignments. It's also not obvious (but you can do it) how to load a profile at startup (put the profile file name after the executable in...
I currently have the Logitech G5, which is probably one of the best mice I've ever used and was thinking of upgrading to the G9.