I suppose this is in the context where you will be syncing up the changes to a backend server which will also be storing the document in an SQL database. Normally, you might expect that data format on the client to be JSON/XML/something else, and you'd need to maintain logic that marshalls the document representation

    SQL <-> In-memory representation <-> Disk format. 

With SQL on the client, in theory you only now need to maintain

    SQL <-> In-memory representation

Obviously I'm skirting over the format you would use to send either entire documents or partial updates of documents over the wire.