I've been using trackballs for many years.  I started with a Logitech Trackman Wheel.  I got a second one when my first one stopped working.  But when they stopped making them prices soared ($400+) so I looked for alternatives.

The wired Logitech Wired Trackman trackball. (source: Logitech)

I tried the Kensington Expert and continue to use it at home.  It's got Bluetooth, is symmetric so it works for right- and left-handers, the scroll wheel ring works surprisingly well, but it's big and heavy and the ball falls out if you tip it over.  Great for a desktop but it's no good for travelling or commuting.

The wired Logitech Trackman Marble doesn't come with a scroll wheel but I guess the buttons on the side are supposed to make up for that.  I could never get the buttons to work on my Mac so it sits in storage.

I had given up hope.  But then my student, a mechanical technologist that uses trackballs for CAD drawing, convinced me to try the wireless version of the Trackman Wheel: the m570.  It's great! It feels like the original Trackman Wheel, minus the cable.  The battery lasts forever and it's super responsive.  Works on both Mac and PC without special drivers and it's super portable.

I thought that I was set.  But then laptops started losing USB-A ports.  My tablet only has one.  That means that without a dock I can't use more than one USB-A device.  The m570's USB dongle is a problem in this almost-post-USB-A world. The solution is a Bluetooth trackball, but Kensington Expert isn't any good for travelling.

Finally, Logitech came up with a solution: the Logitech Ergo.  It's an updated version of the m570, complete with Bluetooth.  It doesn't need a dongle, but you can use the supplied one, if you want.  The neat part is that the dongle can be used on a second (non-Bluetooth) computer and you can use the 1-2 button on the trackball to switch between the two.

Performance-wise, on a Windows 10 PC, it's great.  $120 great? Not really.  It performs as well as the m570, but with Bluetooth.  I'm paying $60 for Bluetooth. The trackball works very well.  The scroll wheel is nice, too.  The up-down buttons work as back-and-forth between webpages option.  The cursor precision button works well, too.  The magnet-attached tilting base?  A gimmick that I quickly grew to appreciate.  I now default to using it in raised mode.  it's more comfortable.

The two design flaws?  First, there's a micro USB charging port.  Feels retro.  USB-C would have been more forward-looking. But why not permit the user to go non-wireless using that wired port? Seems like a no-brainer to me.  Second, unlike the m570, there is nowhere to store the USB dongle.  Another nearly-no-cost no-brainer to me.  Especially for a premium-priced (more expensive that any Apple mouse!) trackball.

Am I happy with this trackball?  Yes.  Should right-handed trackball users get one?  Sure if work is paying for it or you need a stocking-stuffer for Christmas.