"Maybe the best trackball for the money. Not perfect."3.5 starson by DWFII
Pros: ball rolls smoothly, scroll works good
Cons: buttons not long enough for easy thumb access, too hard to reach with index finger and pinky simultaneously.
Summary: I've had trackballs almost exclusively since I began computing 20(?) years ago. Started with Microtech. Eventually went with Logitech and now the Kensington.
There is no trackball out there that is perfect. Few are even adequate. The Marble Mouse and the Orbit are both pretty good. A blending of the best features of both would come close to idea.
The Orbit is too wide...I want to control the ball with my two middle finger and left click with my index finger and right click with my pinky. It is difficult and I am always reaching with the index finger. I could probably switch to a left click with the thumb but buttons don't extend to the rear enough to make them easily accessible. fix those issues and add lazer tracking and this trackball would be terrific.
The Marble Mouse has good button positioning but the buttons don't like being activated everywhere. I have worn out two, grey on grey (newer), four button Marble Mice by clicking with my index finger at the extreme forward end of the left button. It's cheap construction--I have an old (white MM) and it is still working great. The lack of a scroll ring--it could be placed under the buttons--it a big drawback.
Have also tried the very expensive LazerTrac. Not my cuppa...very awkward to use.
Bottom line is that the Orbit is the best of the best at this point in time.