I'm one of the lucky testers of 23andme's new Ancestry Finder, which I think is bearing out the theory you elucidated. At 5cM, using only old world countries, I'm 1.4% UK, .7 Ireland, .2 Spain, .2 Netherlands, and .2 Italy. Adding colonies: 26.1% US, .5 Canada, .2 New Zealand, .2 Australia...