Right now I am using the Logitech MX 620 (a less-expensive sibling to the Revolution but still great) and I also have experience with Logitech's line of trackballs, namely the TrackMan wheel. Though it takes some--a lot--of getting used to it is actually really useful especially for reducing stress (for all you big-screen users) because you move only your thumb. After practice, you can get really fast because it is only the thumb doing the moving. Hope that helps.