best buy seems to be carrying the razor diamondback now. So try going into your local one to see if they have it set up. The two i went into, one had it in the box and the other had it on the floor opened.
Well i was able to test out both mice in my hand. I felt that the razor was way to small in my hand. I practically dragging my hand around under it. I like how the mx518 feels. The button placement wasn't that great on the razor to boot. Personally if you can test them. I would go with what...