it depends on each individual's feeling with the mouse...
like some people can use normal mouse and play good with some games...some people need special mouse...
i've seen pro US counter strike player play with razer krait and sensitivity 14...
yet he's pro...

if the mouse shape fits your hand's grip, it can improve your playing performance...

if me personally i will try to find the most suitable shape for my grip...later on it will be very easy to get along with it...

my mouse is Logitech MX518 now...suits me really2 well..
mousepad is Everglide Titan Fnatic...the color of the mousepad improve the lift off for my mouse and i can lift my mouse around 0.5 cm and the pointer still move...improve my performance for counter strike...