It will be a fresh install. If you decide to go back it, you have to wipe out
the newest kernel and replace it with the edgy one. This is very difficult for a
even the novice user. Because it does not all ways work. Because some of the
software like firefox is tied into the kernel and you end up with one broken
system and have to reinstall from the get go. Thus it is not advisable to do so.
Why do you want to go back to Edgy?