you would need to be prepared to cull the babies that will not be able to thrive, from kinking, a deformed mouth/jaw, or both. the probability of this is extremely high, which is why most people just refuse to pair two Cinnies.
that said, my Super Cinnamon is about as perfect as a Super Cinnamon can be. however i myself will likely never pair Cinny x Cinny.
EDIT: the link @bcr229 posted above is packed with info.