As someone who has bought a US spec GSA while stationed overseas, the only difference is the EPA stickers on the under front side of the gas tank and that all the clear plastic and tires has DOT marked on it.
Items like LED turn signals etc could just be country specific. Like my GSA has bulb turn signals and the UK version has the LED as the LED is not officially approved by the DOT safety yet (even though you can buy them and install in the states).
From what I know of people who looked at importing EU spec bikes and cars, it would not be worth the money to get to US standards as it can require a lot of items to replace. Not that there is a difference between some of the items it the main thing that it does not have the DOT etchings or the US emission stamps/paperwork on it.