I wouldnt necessarily agree . Most are insured for ANY pilot who is qualified and with the permission of the owner , and there may well be an age stipulation ( usually 80 and could be min no of hrs which i have )
Great advantage of the US licence is the ability to fly ANY medium / light helicopter without a type rating ( saves you a fortune keeping all your types up to date ) , No specific night rating needed . Also you can fly G reg pretty much all over the world .....the other way around and you are confined to UK airspace . For most GA pilots the FAA ticket is a much better one to have in every respect in my opinion .