Yea the mx518 was an awesome mouse, but I dont like how much grime and dust and gook the rubber grips permanently attach to themselves. I had the mx510 and my ribber grip thingies had dead skin flakes in their grooves, gross, but i got used to it. I got the Logitech G500 with a razer scarab gaming mousepad about 2 months ago. and it has a totally different hard rough, dry surface that never stains or gets mucky. Its got a sandpaper like feel to it, and i dont feel any grip really being lost to the rubber ones I had before. I added thick teflon aftermarket mouse pads to 100% cover the mouse feet, and left all the weight cartridge + weight out of it. The thing slips and slides all over the mouse pad, like on an air hockey table.
My favorite thing about the g500 is its lack of rubber grips and on top of that a body style that will never look dirty. It doesn't get stuck to gook like the mx series did with those sticky rubber grips.
Most likely though, this new mouse will be better than the g500 i think in terms of control and feel, which is far more important than the useless 5700dpi that my mouse puts out. The mouse under optimal settings in setpoint, 5 speed 0 accel, all options tuned to maximize precision, 1000hz polling, you will never need anything above 2000dpi. I personally use 1400dpi, and this was after an entire month of obsessively trying to squeeze every last bit of accuracy out of it. I can do 1x1 pixel squares in paint over and over, even with 2000dpi, but anything over that is just too much.
I dont even understand why they make mice anymore with over 3000dpi, seems like all a marketing gimmick, since its never going to be used practically. setpoint settings 5 speed/ 0 accel, windows driver disabled, will give you as close to a 1:1 accuracy as you can get. So if you WERE to use anything over 2000 dpi, you would need to drop speed level, in which case the setpoint driver is deleting a good amount of the input, meaning your mouse is fighting your operating system's setpoint drivers to give you your desired speed and feel.
I am happy logitech left the dpi at 3000ish, at least there its not a total waste like 5700.