Not sure about the scroll ball myself. Microsnot has a tilt wheel thingy that's supposed to do horizontal and verticle scrolling. I've got a trackman myself (corded, haven't gotten into the cordless thing, I still remember when it was new and sucked), always been addicted to Logitech peripherals, great ergonomics, great feature set, and amazing durability. This "new" Apple mouse has caught up to where Logitech was back in 97 or 98 (except for the scroll ball, they just had a scroll wheel back then), for about the same price Logitech was charging back then.
I tried a Microsoft trackball once; never could get used to the un-ergonomic setup (I don't have Andre the Giant-sized hands, which is what Microsoft made their trackballs for). I don't feel like burning the desk space for a mouse, so those are out.