For me, with digital currency or any other form used for barter, I'd never hold it, unless it was backed by the full faith and credit of the US Treasury.
I'm not a "big" government advocate, and I understand our currency is no longer back by Gold (purely fiat), if I were ever to hold another currency, it would be one that is backed by the full faith and credit of a Treasury more stable than the US. At present, even now, no other comes close (this is open to debate, I know).
Every country's largest currency holdings are in US Dollars. The greenback is the world's de-facto currency, and therefore, because of that, isn't subjected to the normal forms of devaluation we've seen other currencies endure.
Until a "digital" currency can approach that sort of standard, I don't see anything more than a "dabbling" of one's resources, purely for fun, into currencies such as bitcoin.