I had a razer deathadder. The shell was improperly made, causing it to scrape terribly against the mousepad, drivers were glitchy and screwed up the settings for other devices every time the DeathAdder was plugged in, and, as a fingertip grip user, I just couldn't get used to the shape and weight of it. The sensor may or may not have lived up to its reputation; I was too busy being pissed off at the thing to pay much attention to the nuances of its tracking abilities. A few months in, I took it apart, and, somewhat to my relief, it did not survive the process.