The conditions referenced in GP seem to imply that the most general state-based CRDT is simply a set of all reported outcomes. Something commutative, associative and idempotent is basically describing set union. So whether it's easy to go from one to the other would seem to depend on what constraints you're enforcing on your database.

Operation-based CRDT's are a bit different, these require commutativity and associativity. So you would be dealing with a multiset of reported operations.