So if you load Ocean Basemap into a new Flex application (etc.) the JSON reports this Full Extent and when the user pans "off the edge of the world", you get lots of failed tile requests, because they don't exist but the map viewer clears a large enough area for the new tiles which makes it look clunky.
Only way around it at the moment is to define your primary basemap as one of the ones that does work then overlay the Ocean Basemap over the top. Not ideal as doubles tile requests/bandwidth