I still use a Kensington Orbit with my daily driver, set up as a left-hand input device.
It's for when my right hand is, uhhhh... busy. 😊
Seriously though, I learned to be ambidextrous with input devices over fifteen years ago. Carpal Tunnel Syndrome is no joke and it doesn't discriminate.
I only keep this old trackball because I paid for it with money, it continues to work, and it's worthless on eBay or craigslist. When it dies, I won't cry. It's really not a great input device but it does the job adequately. At one point I was going to use it with Red Baron 3D to track enemy planes. I may still re-purpose this trackball for that sim someday in lieu of Track-IR support.
I also still have an old 2-button, serial, Mac-style, Kensington "Mouse In A Box". I don't use it anymore. I just keep it out of nostalgia. Back in the day, I remember loving it until the first 3-button, scroller-wheel, wireless mice became available.
Cleaning ball-mouse rollers sucks. Fortunately, my Kensington Orbit trackball only needs attention about once every four months.