[kmcgivney]

While you are correct that the population of the USA is around 300 million, the population of the UK is roughly 60 million. Of course both numbers are presumably more than the "target" you are talking about, but I think it's safe to say that Great Britain is about 20% of the size of the USA.

Also, I don't understand the growth-rate math. Why would the UK company have 1/100th the number of users?

How much would the variety of English you use on a website alter your traffic? I'm asking because I really don't know. Does anyone have research on this?

[thirdusername]

I can't point you at research but I've recently found that it does seems like my American friends have a much tougher time understanding British-English than I do as a non-native English speaker and from my experience non-native speakers don't care what version is used as long as it's consistent (for those that care a little at all). Personally I don't really notice if I'm reading American or British English, I only notice when it's pronounced.

I too would love to see research.