At a simplistic level it's worth thinking about the growth rate...

At a simplistic level it's worth thinking about the growth rate they are having in the USA as well as the potential market size over there.

Could assume it will be difficult to maintain the staggering growth, but even if the growth declines, if it stays elevated it will have quite a significant influence over revenue as the growth compounds year on year.

If I was already in, I personally would hold. I was hesitant because the USA was unknown, but they are getting some real traction over there so it looks more interesting to me as a latecomer now.