<< the Microsoft Intellimouse Explorer 3.0 (silver, right handed)/Microsoft Intellimouse Optical 3.0 (white, ambidextrous) both track much better than the logitech duals....i find the duals to be pretty ineffective on most surfaces. >>
I have a dual and I have to admit, it didn't like the el-cheapo pad I bought at the time: it was skipping all over the place. I'm now using a pad with a matte surface and I don't get tracking errors, EVER. The mouseman dual optical kicks ass!
-Ice