I recently purchased a Jelly Comb MT50 trackball as a replacement for a dying Logitech M570. I don’t know if it’s objective, but the M570 buttons seem to be less sturdy than they used to be… My friend Joe repairs a lot of M570s and suggested I get one.
It looks good. It feels good. There are some differences that almost escape you, such as the fact that the button cover is one piece, split and flexible enough to use for individual buttons.
There are differences. The battery is internal, not replacable (unless I send it to Joe or another tech), and rechargable. It turns off when it becomes idle, rather than waking with your mouse usage, and you have to physically turn it off and back on when you boot if it has been longer than a certain amount of time.
It charges with USB C. Or, and here’s a big difference, if your computer has current Bluetooth, it can not only run as a Bluetooth device (and not use your WiFi signal or the dongle at all), it can charge via Bluetooth.
The price on Amazon is similar to the M570, so the difference in pennies you pay should not be a factor in choosing either trackball. You’ve never heard of Jelly Comb? That could be a factor.
This looks like a better trackball, feels like a better trackball, and probably, down the road, will continue to be a better trackball. It’s not any single thing that makes it stand out: other than the Bluetooth capability, there is nothing that would make you want to throw your M570 away and buy one of these. But that M570 is going to die, or stop working as well as it used to, sooner than you used to be able to count on for a Logitech device, and it is my opinion you should strongly consider replacing it, when it does, with a Jelly Comb MT50.
Moss
Update Nov 30, 2021
I got a chance over the past few days to try the Jelly Comb MT50 as a Bluetooth device. It seems to work better on some machines and in some distros than others, but if you can get it to work, it can save you dongle programming or extra trackball purchases.
I also discovered that you don’t have to turn it off and back on when you start your machine, just have to hit the button to select Wifi, Bluetooth 1 or Bluetooth 2 — one quick click and the device is on. This reduces the point of friction noted above. Just remember that you need to keep it charged.