[Zope] Q: Advantages of storing ZODB in RDBMS

Can anyone explain what the advantages are of using an RDBMS for Zope object storage over the standard file system storage? Is it simply the convenience to have the data in one place (for backup etc)? Does it scale better? In connection with ZEO? I'm asking because I'm contemplating writing such a storage for a specific RDBMS and I would like to know whether it's worth the trouble. Daniel Dittmar