I move the mouse from one side to the other and switch hands, every month or two, so as to avoid overuse injury to the wrist. Doesn't seem like any big deal.

I'm strongly left-handed, but play guitar right-handed because I didn't know I had a choice when I was learning. As a result of that, I fire pistols larger than .22 right handed, because the tendon between the thumb and first finger of my left hand has gotten shorter from all the years of mashing the frets on down, and recoil bothers it.

P.