Two responses:
1.  No, I have not yet tested on a distributed instance of Accumulo, but I'm happy to do so.
2.  Although it is true that we could read the ID from the key, we may not want to do so.  This PR is still, with luck, a stepping stone toward a scheme in which the ID is fully removed from the Key (once we can build our unit tests to use mini-Accumulo in version 1.5+).