Somebody posted some graphs showing how fast various mice could track on various surfaces. I have a Logitech G9 and an Icemat, and the tests said this was a poor combination. But I had never noticed any problems. It depends what type of gaming you do and how fast you want to move the mouse (if you use low sensitivity you'll sometimes need to move the mouse fast and far.)
For me the Icemat was the best thing I'd ever used. If anything the amount of friction was too low, any tension in the cable would drag the mouse along when you let it go, so I used the heaviest weights in the mouse to counteract that, lol.
The only reason I stopped using the Icemat is I got annoyed how mats divide your deskspace up and constrain how you work. But I'm missing how well it performs, so I'll probably go back to using it soon.
EDIT> Found
the thread. Here's the Icemat graph:
My old G9 fails before 1m/s speed is reached. The newer G9x and others get closer to 4m/s.