I have my new 64GB PlayBook next to my wife's 16GB. Hers is over a year old, mine is less than a month. Hers is on OS .668. Mine is on OS .358. Mine says it has the latest OS when I click the update button. Hers just had a 3MB update because we're in the US at present where more stuff is available.
While the situation is not as cut and clear as that, it sounds like you are good with the information you have, but if you have anymore questions let us know...