In both Iceland and Greece you saw a massive loss of trust with the existing government (both since replaced democratically)- that has nothing to do with peoples faith in their currency, as you've not seen a real call in either place to go back to a specie backed currency.

In Greece there have been calls to go back to the Drachma - but this doesn't mean a lack of faith in fiat currency, the greeks seem to more want out of the EU currency union then anything else.