I'll have to look into those derivations. Thanks.

> There is an additional postulate, namely that the state vector is the real world we inhabit.

Well, yes, it's a model for the physical world. Refusing to accept that the state vector is the real world we inhabit is tantamount to rejecting the existence of an objective universe, in which case any discussion is moot, or to the outright rejection of quantum theory, which seems irrational. (i.e. "I don't believe the state vector represents our world, despite it being the best physical model of our time")