Hmm, there's nothing on the announcement about how to upgrade your existing backups? Say you have a large backup stored on S3 or Google Drive - has anybody use

Hmm, there's nothing on the announcement about how to upgrade your existing backups? Say you have a large backup stored on S3 or Google Drive - has anybody used this, and can tell me if it upgrades it seamlessly to take advantage of the new features (e.g. LZ4 compression), or if you need to do a fresh upgrade?