basicly the live rock rubble and the ceramic rings are the same thing, the advantages of using live rock rubble, is that the bacteria is already built up on it and it probably speeds up the cycle pretty effectivly. It would be like taking and putting base rock in there instead of LR rubble, eventualy it will do the same thing, but initialy it will be alot better.
atleast thats what im assuming would happen, if you think about it, it makes perfect sence.