I'm not convinced that you can legitimately attach the label "Wagyu" -- especially is it's a cross, which I assume the X means -- to beef which doesn't come from cows treated palatially like those in Japan, complete with special feed and beer and massages, it's not just the breed it's how the cows are raised.
Which explains the ludicrously high prices there (also Kobe beef, just as delicious -- or Matsuzaka beef, very similar) as well as the quality, and the reverence with which a chef there treats it, none of this "well done" rubbish -- and if you had the temerity to suggest mincing it up to make a burger you might not make it out of the restaurant alive... π
I have a photo somewhere of a butcher's window in Asakusa with a gorgeous piece of Kobe beef weighing several kilograms, and at first I though they'd mistakenly put an extra zero in the price because it cost rather more than my return airfare to Japan... π