I believe FinCEN is right on this and any regulators saying otherwise are blowing smoke, or simply don't know what they're talking about.  BTC has no guaranteed cash value.  It is a thing that has value because people will pay for it or accept it as payment, but unlike a prepaid card, sort of the definitive example, no corporation or government backs up the value.

Not to say that it's beyond regulation, but stored value is a particularly poor fit.