First, where was this quote from?
Next, Hundres of Thousands of US Citizens hold dual citizenship with varrious countries in the world, some of them post here on these forums. So far I have never heard of a case where anyone has lost their US citizenship by swearing an oath to the queen or obtaining and utilizing a UK passport.
Tax evasion in all of its forms is 100% illegal. As far as Im aware all US citizens residing abroad, temporarily or permanently, must file a US tax return. The US cannot charge a tax on income made 100% abroad if your income was under the maximum threashold for the year. I think 2003 was somewhere around the $80,000 mark. Anything over that figure was subject to US tax regardless. A US citizen who makes ANY form of income weather in the US or aborad should NOT avoid filing US tax returns simply because they live abroad or hold dual citizenship.
The general rule is that the US does not recognise dual citizenship. If you are on US soil and you are a US citizen you cannot claim assistance or protection from the UK, such as through its embassies and counsulates. If one where to join HM Forces and the US went to war with the UK - you might have some problems.
The US likes its citizens to enter and leave the country on a US passport but not doing so will most likely not result in losing one's US citizenship. Unless you're reckless with your dual citizenship or your countries go to war probably the only way to lose your citizenship would be to formally renounce it.
If you want it - get it. Theres nothing to worry about. As I said before, hundreds of thousands hold dual citizenship and generally have no trouble, as far as Ive ever heard. These dual nationals have been born abroad and naturalized in the US, born in the US and naturalized abroad, and many of them are ENTITLED to hold dual citizenship by birth. The US isnt going to go revoking the citizenship of a US born person simply because theyre also entitled to citizenship in another country as well. I dont see why they would treat naturalized dual citizens any differently.
Thats my take anwyay.
Sarah