But... The first and obvious observation is.. that it's exchange related, most volume ("speculative and investing") that goes through and peoples holdings are with MTGOX. If you can't get your money out, there's a loss of confidence. And that's obviously all that matters for a currency.
If you bought it at MTGOX right now in size, and sold it in size on the others, theoretically yeah. But There's a liquitidy risk problem to deal with. But if you're small size, try it.. I could try it, but i don't know about it.. since i'm not sure wouldn't be able to get out and convert bitcoins to regular moneys to buy a (suit, computer. etc..) . Fundamentally to take my moneys out of MTGOX.
I don't look at bitcoin as a currency as the GBP or EUR or DOLLAR IMO, it's possibly a currency in the form of memory. So they can coexist, and the environment is the key to that. :) Google kocherlakota "money is memory". that's my two cents, or two bitcoins ;)