Just for the fun of it, I have posted screen shots of the estimates of my ethnicity from three testing companies. For the record, I describe myself as half Irish and half Welsh (UK) as my father was Irish and my mother was Welsh.
(i) Family Tree DNA
Family Tree DNA
(ii) Ancestry.com
Ancestry.com
Ancestry.com map
(iii) 23andMe.com
23andMe.com
Genetic Genealogist 
I think I will order a test from Ancestary.com and compare those results to Family tree DNA.
Thanks for posting. I was wondering how different the results would be from these sites.
Perfect article.