i have 3 now, and a 4th one coming in..
the Logitech Trackman Marble and Logitech Trackman Wheel (Optical) are both nice. i've overclocked them both to 1000hz (up from 125hz) which makes tracking considerably smoother.
neither of them seem to have any acceleration, which is how i prefer it.
the Wheel seems to have some 'angle snapping', but it's hard to properly test this since the ball doesn't move around smoothly enough.
overall cursor performance seems smooth and precise on both.
nice buttons on both. not sure what the marble uses, but the Wheel uses chinese Omron switches.
M3 is a bit mushy on the Wheel, but it's no biggy in my opinion.
i can definitely recommend these two trackballs. i do wish the balls were a bunch smoother, though...
the third one i have is a Microsoft Trackball Explorer. its polling rate becomes unstable when overclocked, so i returned it to default 125hz.
tracking is very jittery, and there's obvious acceleration. M1 is extremely mushy.
the ball moves considerably less smooth than the Logitech ones (and the Logitech ones aren't even that smooth).
i got this one because i read good things about it and that got me all hyped up, but i really can't recommend this thing.. ( unfortunately i paid a ridiculous amount because it was NIB and i wanted a scratch-less ball
)
i'm considering Kensington and CST, but they seem to be a bit more expensive.
are the ones from Kensington and CST plug-and-play? (i prefer not having to install any drivers or software because i use so many different peripherals, and i'd rather not install 20 different pieces of software for all of them..)
is the tracking precise? is the glide of the ball smooth?