Return the steak if it is not how you want it. The metric system hasn't changed since its inception and the idea of how hot a steak should be on the inside in order to be classified as R, MR, etc, hasn't changed. If it's not as you want, send it back, but be sure that you know what each temp should be. The overcooked part of dining can often be explained by restaurants that keep food heated on the line until the server picks it up. If they don't get it right away, the meat can easily be cooked up a grade or two. If you're finding that one place is over/undercooking commonly, then mention it to the manager. Another alternative, would be to request that they use a meat thermometer to make sure of the temp on the inside. In any case, the difference between R/MR and M is quite a bit and a cook/chef will definitely know once the meat is sliced open. If you want more info, I'd suggest heading to a bookstore and reading through the meat section of something like Professional Cooking. Hope this helps.