It is beneficial if you leave the country. Documentation states that your vessel is a member of the fleet of the USA. Therefore, if a country seizes your boat, it is seizing a US vessel which carries more weight if it is not documented. On the down side, if the Government needed it, it could seize your vessel for an emergency. (think Dunkirk) which is very unlikely. I discussed this with a yacht captain who travels abroad alot, and he is strongly in favor of documentation.
