When I did my initial block download, I was of course upset about it taking a week to download...but at the same time I was excited to think about the history of that entire ledger and proud to become a full archival node.

We have to be careful about this new thing for sure. We need some mechanism for nodes that use this method to receive some kind of warning from peers. Maybe peers can create a hash of their own utxo set and communicate this hash with the baby node and warn the user if the hashes don't match from the peers they communicate with.