Official is official, yes. Official sources may be wrong, however. A textbook example is the Star Wars site that stated that the Super Star Destroyer was 8km long, when this was clearly wrong. They revised it twice, with 19km being the final, and much more logical, value.
In this case, however, the official word on the size of the ship, and every piece of evidence we have, point to the same size: 700m+.