To date, I've not seen a blockchain data dumping scheme that could not be securely replaced with a simple hash.
You don't need to store
data in the blockchain. That is purely intellectual laziness. Timestamping hash(data) is just as secure, while more efficient.
Furthermore, a secondary chain can be provably pegged to bitcoin:
http://sourceforge.net/p/bitcoin/mailman/message/32108143/While you are here sir, interested to know why the QT client still has bugs - I never got a response on the newbie forum: