Slimblade doesn't have good reviews overall. Altho I don't personally have any experience with it.
I have used Track Man (worn out and discontinued), Trackball Marble (still in service), and now the M570. They're all pretty good.
Trackball Marble: Finger based with big trackball, which gives you really smooth and precise control once you get the hang of it. However, I really wish they could somehow integrate scroll wheel into it similar to that of Cordless Trackman Optical (Not so good review and old wireless technology).
Trackman/M570: Thumb based with smaller ball. Still work pretty good once u get the hang of it, but your thumb would be quite stressed under long period of use (but nothing like smashing D-pad on ur Playstation game pad all day long though). You do get to have a more standard button layout and additional 2 programable buttons with M570.
Touch pad: My experience with touch pad is limited to the WACOM version but then it can't be too different as far as usability is concerned. Simply put, touch pad isn't ergonomic at all IMO for extensive use. You will still end up with a lot of wrist movements and the one I used also put quite a it of strain on fingers for some reason...
If you dislike Logitech and would really like to go for Kensington, skip the slimblade (i know it looks slick) and go for the Expert Mouse. Solid reviews as far as my knowledge goes.