Does BU even have replay protection ATM? From what I understand, they may fork it if they have over 80% of the hash, but what happens if the tide  turns, and the CORE 1MB suddenly has more than 50% of the hash? When the small block chain eventually takes over the BU fork, are the BU nodes going to switch to that chain and basically erase the forked chain from memory? That would be a disaster for anyone running the BU chain.