I moved from ball to opti-scroll a couple years ago. I noticed the same lack of precision....changed mousepads to a more varigated surface and image, and it seemed to do the trick. Those light beams need to have something to detect when they're moved over a surface. The worst was a reflective white-board kinda mousepad. The best was a multi-colored, rough surfaced pad.

Now I've made the switch to laser (the Logitech MX1000). It can detect motion on ANYthing, it seems - even my naked knee (I have a laptop).