I never used anything other than the pearl wit the trackball but I believe the next iteration should use an optical pickup, afterall, that's what happened to the trackballs in mice!
The wheel was alright until you ended up with a web page with more than one column of links. With the wheel on the 8700 I could not get it to select a link beyond the first column.
Anyway, get used to the trackball or switch devices. The last OS they wrote for the 8700 was 4.5. They won't be releasing anything newer and after a while it won't be practical or well supported.
