Nice review.
I have a Clearly Superior Technologies CST2545W-RC. The device is quite large, and quite expensive. But it’s very comfortable in my hand and feels well built. It has 3 physical buttons and a separate scroll wheel, which I like so I don’t accidentally middle-click while scrolling. All the buttons are large so my hand can be in a comfortable position and still easily click. Each button as a satisfying actuation also. Sadly, CST is out of business but you can still find some on eBay. Not mine, though!
It works fine in Linux:
Bus 002 Device 002: ID 5332:1400 Clearly Superior Technologies. CST Laser Trackball
I doubt there will ever be any firmware updates considering the manufacturer is defunct.