The Razer Basilisk's thumb clutch and unconventional shape are winners, but is it really a better FPS mouse than the DeathAdder Probably not.
Adjustable thumb "clutch" easier to use than any sniper button; Comfortable thumb rest area; PWM3389 sensor closely related to the familiar PWM3360
Unconventional shape might dissuade some; Scroll wheel resistance is adjustable; but hard to get set properly; Beta version of Razer Synapse is still...