Hardened derivation requires data of the personal keys to have the ability to derive extra public keys. Since each Casa and their buyer solely management a subset of the personal keys within the quorum, neither would be capable to derive extra addresses with out interacting with the opposite celebration, general activating each personal key within the quorum. This could be arduous given the meant setup with the client’s {hardware} wallets in a number of areas and one of many keys held by Casa staged in a key restoration scheme. Even worse, if any of the personal keys obtained misplaced, it might not be doable to regenerate any of the prior addresses: solely cash from addresses already recognized could be recoverable, even when the remaining 4 personal keys had been obtainable.

It follows that utilizing non-hardened derivation on this setup gives a greater consumer expertise and arguably a greater danger trade-off.