You do realize companies make sure to game it such that they declare no profits in the US, right? And don't even care that much about repatriating it at all? And do so only when there are "tax amnesty holidays" where money can be repatriated "for free" during a short timespan?
So basically what you're telling me is it's very hard to properly compare the final effective tax rates on corporations in two different countries. The study above doesn't compare to other countries. So you don't actually know if it's really worse in the US.
http://en.wikipedia.org/wiki/Double_Irish_arrangement