Er ... yes ... the euro is a really good idea, and as an idea I like it, but ...
The wider that market, the easier it is to utter forged notes. To offer some ball park figures I picked up from a journo a while back, it costs about £750k to get a pair of plates to print the dodgy money, then you need the right paper - and that costs a bit extra. Unless you own your own country, to justify the matter = and the Mafia own the republic of Domenica, so they can buy whatever they want legitimately, then do what they want with it.
In the days when all european nations had their own currency, forgery was simple economics. It cost about £800k to set up a forgery scam which would return £1.35m to £1.6m to the scammers. The technology has not advanced much, but the mafia have not intervened yet. That might be down to the parlous state of the European economy - don't kill the goose that lays golden eggs - but while we have to rely on paper notes to complete transactions, we are open to forgery as a hazard.
The euro has been a good idea for a long time - as long as forgery can be avoided. We have chip and pin security - let us have chip and pin banknotes to avoid the point where the mafia WILL step in and make money from the euro.
You do not have to be Einstein to do the sums - 18 countries are vulnerable to a direct attack, and 13 countries will give them about €8m for a €1m investment.
What's the choice - nuke Italy?