British Expatriate Network

My wife and I and kids (27 and 25) are all British citizens and have lived in the US for 13 years. We have green cards. I understand that if my wife or I die then the IRS will take more money in tax than if we were US citizens. Is that correct? Also I understand from reading some of the threads that we could hold dual citizenship, US and UK. The last I saw was that the UK recognises dual citizenship but the US does not. Is that true also and does it matter? Thanks:

Hasn't been an issue for me.

Pros, in my experience, include right to vote in all elections;
Only need one passport and US one is cheaper to renew;
Can still vote in UK elections (I have a proxy vote for me);
Feel differently about being here and possibly settle/join in more;
Can switch between criticizing either or both nations and never get called on it

Not sure about the tax side of things - that does sound vaguely familiar - Google would probably confirm this or a visit to the IRS site.