A very long time ago I purchased the Logitech MX518 and loved it. Eventually I upgraded to the G400, since it is the same design but upgraded, and now I need to replace it since it doing double clicks. I would like to know what is the upgraded version of the G400. I would like to only stick to this design since it is the design that I have loved for over a decade. I like to stick to logitech brand, but if there is another good mice out there with the same feel, then I will look at that brand. FYI, I still have my old MX518, only issue with it is that the right click sometimes does not work.