Makes sense if you are going to rebuild anyway. I thought from your post you were doing this just from the reduced number of chickens.
As far as needing a smaller coop to keep them warm in winter, in Georgia I'd be surprised if you have any issues with that as long as you are able to keep...
I am not going to comment on the premade ones. I don't have the experience with them though I'm sure many on this forum do.
My comment is on why you want to build a small coop. I thought you already had a coop. It's really none of my business, but that won't stop me from asking. If you...