If you're careful you can keep a backup trail going all the way back to your original device firmware and restore/downgrade it using the Hekate system tool. It has already been pointed out that there isn't much reason to do this, AFAIK the main reason people either held out on older firmwares or kept up a backup trail to them was in order to take advantage of possible firmware-version-specific exploits, the gold standard being a coldboot exploit.