Pleasant and efficient 3

For a few months I was interested in control ball (trackball) to replace my mouse and I ended up choosing this model.
No regrets so far, the grip was super fast (just 15 minutes!), Though my thumb still tends to make too sudden movements to lateral movement. It is important to manipulate the ball with the tip of thumb, the more specific area, without exerting any pressure on it.
Among the benefits, I note:
- Reduction of muscle fatigue in the back of the shoulder, which is a real plus when you spend a lot of screen time (10 to 14 hours a day in my case, my account in IT)
- Speed ​​and increased accuracy when handling the ball. I note in particular the handling of windows, I move a virtual desktop to another in just moving the thumb, and the speed of copy and paste (almost instantaneous selection of the line or paragraph)
- It's clean and it takes up little space, especially visible after I had unplugged the base, the adapter and the USB cable from my old MX1000
- No driver required unlike the Marble of the same brand. Tested flawlessly under Windows 7 and Ubuntu 14.04.
- And finally, especially subjectively, it's a nicer interface than the mouse of a sensory point of view. The trackball although the shape of the hand without moving, and the feel of the ball that rolls under the thumb is quite nice. In comparison, the mouse which is stirred everywhere rubs, dislocated shoulder, fatigue, and gives an impression of fighting with the machine once you have tried the trackball.

For complaints: roulette, which I find too hard as for scrolling the middle mouse button ... it gives the impression of being taken into the plastic.
The materials are correct without either extraordinary beings, 100% synthetic, do not bother to look for metal or anything nobler. 40, one would have expected better, but alas trackballs are a limited market with very little competition, it does not help to keep prices low.
The quality of finish is good, no games in the assembly or buttons that "float". I read here and there that the pressure contacts can deteriorate over time (several years), but this is not unique to Logitech or the trackballs so I expect to see before I comment.

Last recommendation, the ball should roll freely in its holder, with a slight inertia and without meeting any resistance. My factory model released slightly rubbing (audible friction), which unfortunately seems often the case. Solution: remove the ball from its housing and lightly scrape the edge of the housing, taking care not to touch the ball bearings and the sensor. Personally, I used lime cut my fingernail to remove these asperities release. Since then, it rolls perfectly, without friction or resistance.

Finally, I leave 5 stars rather than 4 because I'm really satisfied, I will not go back to the mouse and the criticism towards this trackball are more negatives than real defects. Feel free to try that of a colleague or a friend if you work a lot on computer, even if you are unable to be more precise than the mouse, you should at least win in comfort.