If they're going to overwinter as nearly dormant sticks they probably won't do much to take advantage of being repotted now. If they are going to continue to have leaves and even be flowering they are more likely to appreciate fresh soil and more room for roots.

Thank you so much. I'm going to wait--this weather is not motivating me to be in the garage!

I agree with bboy. If I'm planning on the zonal geraniums just coasting through winter until spring, I don't repot them out of fear of root rot if they're not actively growing.

If I bring them in to a sunny (okay, sunny for here) warm window and keep them in active growth, I will repot them.

Good luck with yours.
Take care,
Grant