I purchased a brand new black XL at a busy store about a month ago and it was 6.2.
You would have to have some seriously rotten luck to get a >9.2 system. Just do the obvious thing and check if there are signs the box has been opened and make sure the store has a lenient return policy in case it turns out updated anyway. (could certainly happen, especially so soon after the Christmas return season)
I honestly doubt Nintendo will ever make a >9.2 3dsXL given the new3dsXL has arrived.