Cotton Flannel as batting?

I want to do a lightweight batting in the next 2 quilts for the grandsons.  They have moved from almost on the Canadian border to the state of South Carolina, in the USA.  As they both want the "minkie" or fuzzy warm backing on the twin quilts I think that a heavy batting would be too much.  Although the Minkie is polly, the rest is cotton.  Has anyone out there used this?
Or do you think it's a bad idea?
Thanks,
Sara in Fla.