Unless you renounced your citizenship (which I'd NEVER advise any American to do unless you are pulling in Eduardo Saverin type of $$$$), then you still have to file a US tax return each year and also you still have to declare any bank account or investment account abroad that you have over $10,000 in. Yes? (Form TD F90 and Form TD 8938 from the IRS).
On the plus side, you can still exempt $95,200 for yourself in 2012 and you can make your wife an employee as well and exempt another $95,200 for a total of $190,400 a year in the USA from IRS taxes. So as long as you're not in the USA more than 30 days a year you don't have to pay taxes on that income made outside of the USA. I'd assume you are already doing that.
However, from what I've researched, you still have to file TD F90 and Form TD 8938 if you have lots of bank or investment accounts abroad. And honestly, that is what triggers an audit if you have many offshore bank or investment accounts over $10,000. (Take it from me as I've gotten audited 3 times out of the past 6 years). It's a major pain and I've worked to close down most of my offshore investment accounts because of this. Fortunately I've always declared all of them outside of the USA so I avoided problems. I stopped getting audited once I closed down most of my offshore accounts. I still have a few and fill out the TD F90 form but not nearly the amount I had before. I honestly believe those trigger audits.
And you do NOT want to get caught not declaring these offshore accounts. These days there is no such thing as "offshore account" anymore. Almost all of these countries share information with the US government now.
So that's something to think about. I also thought about getting citizenship in Argentina but never went through with it. It's true that foreign countries do not want to open new accounts for Americans. But fortunately I already have banking relationships outside of the USA so don't have to worry about that. None of them shut my account because I'm American. It's just that most aren't opening up new bank accounts for Americans due to reporting hassles.
Plus, I still have to declare all the accounts outside of the USA. And I hear that soon the IRS will start making Americans declare real estate they own outside of the USA. I think it will take a few years for that but that will really bite when that happens. And once they announce that...you're going to have a lot of Americans scrambling to sell real estate offshore.
While I think E.E. has a good list of valid reasons. Personally I just didn't feel like they were a big enough incentive to me to hassle with it. That could change in the future but I can accomplish everything I want on my US passport. Staying on the right hand of the law really prevents a ton of problems. And when I want to go to Cuba or Brazil or any other country it's still possible. More hassles and paperwork but still possible.