Thanks Oli. That's what I was afraid. I will try to email them just for curiosity.
I haven't had much time to look into it, but I opened the Steelseries website and I really like the design of those mice, they are ambidextrous by the look of it, and your feedback is incredibly positive so that might be my choice in the (near) future.
Sigh, lots of money going out... I also want a gamepad (waiting on the XOne only to see the Steam controller at the next event) and need good headphones as well.