With the trackpad on my Laptop, I switch quite frequently and haven’t yet noticed any difference in precision. The movement is very different than mouse or pen control though and comes more from individual/multiple fingers instead of the whole hand or arm, so I guess that explains it.
At work, I don't use a left handed mouse. Just those cheaper but common symmetrical ones. And I don't bother changing handedness. I just pick up the mouse and put it to the left of the keyboard.
shrug It works.