Tried out the Kensington SlimBlade trackball over the weekends and I liked it a lot.

My index finger got sore from excessive scroll-wheeling and mouse-clicking recently and I shopped around for more ergonomic alternatives. It's a shame that pointing devices as futuristic as trackballs didn't gain more traction: I blame the prevalence of flat design. To be fair, not all of the trackball designs seem that confortable to use. I didn't like any of the recent Logitech offerings (all thumb-operated/wireless trackballs). While it's nice to have open source offering in this space, Ploopy's scroll-wheel implementation seemed no better than an ordinary mouse. The SlimBlade seems to be one of the few trackballs has integrated scroll-wheel functionality as opposed to actually adding a scroll wheel. The CST/X-keys L-Trac was the only other contender with very well received free-spinning scroll wheel, but I preferred the size, design, and lower profile of the SlimBlade.

Back to SlimBlade: I did need to apply some Vaseline to get the ball to spin freely in its socket at the beginning, as the one I received does show some age. Instead of storing settings on-board, SlimBlade relies on it's OS-side driver software, which means on Linux we need to go through X-org/libinput for customization: not that it needed much at all though. The scroll-wheel function utilizes the vertical axis of the trackball and produces a very satisfying click when activated. The official demonstration features the scroll-wheel function with a holding-a-knob gesture; some user reviews I read indicated another common way is to hold trackball in place with one finger and pivot it using another; my preferred way is to rest one finger on the metallic ring outside the trackball and scroll away. Despite the SlimBlade's low profile, I find an old ErgoDox wrist rest to be just the perfect fit for an even more comfortable hold. I'm really happy with the experience so far - looking to replicate this at work if I feel tangible long term improvement in comfort.