I suggest trying Logitech MX 1100 mouse.
There is also 1100R model with the ability to charge the mouse via usb.
The R model is officially only Win-mouse, but works just fine with USB-overdrive.
Anyway, the MX 1100 fits perfectly to my hand and the hidden thumb button is so good for expose or something you use regularly.
I've tried Performance MX as well, but I have to say that 1100 beats it IMO.
At least take a look... I suggest it highly. It should be a bit cheaper also.