Some time ago, the Evoluent Vertical Mouse
I've been using at work has gone unusable (was a VM3 - it's ok technically, but it's rubber coating is gooey after a couple of years of use, very uncomfortable to touch), and so I thought - why not just use a normal mouse, with the left hand for a change.
Yeah well. That's harder than I thought. Precision is not a problem for normal tasks (I often use the left hand to handle tools), but using the mouse still needs a lot more attention right now. I hadn't realized how hard-wired these things are. With the right hand - even when using the Vertical Mouse, which enforces a slightly different kind of arm movement - just takes no conscious effort. I think I'll try for another week, but right now I'm taking a sharp hit in effectiveness while doing anything that needs the mouse. Even in the small things, like habitually picking up the coffee cup with the left hand, and then noticing I'd need that hand to click on a link right now...
I also noticed that I still use the left mouse button for left clicks (with the left middle finger), instead of the index finger on the right button. With Windows, that's actually an advantage, because the local mouse settings don't map into terminal service sessions, and I'd have to change the mouse settings on every system I connect to otherwise.