I would say it's not fundamentally different from liquid except that:
  1. It uses Chaumian cash, which means all transactions within the federation are inherently private
  2. There's a greater degree of interoperability external to the mint (lightning and on-chain transfers)
  3. It should be easier to spin up new federations.
If all or a quorum of federation members disappeared, yes, you would be rugged. If you already have sats onchain or a lightning node, I don't think there's much benefit (beyond possibly some anonymity when spending.) If an onchain tx is looking really expensive for you, and you just need to be able to send and receive to a hot wallet cheaply and somewhat privately, this may start to look appealing. Well, more appealing than a traditional custodial wallet certainly.