Assuming a strong form of encryption with minimal information leakage, avalanching would imply that flipping even a single bit of plaintext in a volume of N bit

Assuming a strong form of encryption with minimal information leakage, avalanching would imply that flipping even a single bit of plaintext in a volume of N bits would force ~N/2 bits of ciphertext to change with a distribution approaching maximum entropy. Flipping any number of bits should have the same statistical effect. Of course, that's infeasible for file system encryption and isn't how TrueCrypt works. An idea is to use a one-to-one mapping between TrueCrypt blocks and DropBox files. Write a file system watcher script that picks up changes to files in the DropBox folder and mirrors the changes to the corresponding blocks in a TrueCrypt volume that lives outside the DropBox folder. The other way around, too. Do you see anything obviously wrong-headed with this approach? I admittedly don't know the details of TrueCrypt's crypto. If it already does file-level rather than block-level encryption, these tricks wouldn't be necessary. But file-level encryption would seem to leak way too much information to satisfy the truly paranoid.