Johnston, yes it takes about 50 to 100 hours for the new ribbon's to "burn-in" and really blossom. As far as I know Magnepan has not recently changed anything physical when it comes to their ribbon tweeters, I recently replaced my ribbons in my MG-20's and did not notice them to be thinner then my older tweeters. About ever three years, depending on how many hours you put on your speakers, if you replace the ribbons your Maggies will sing at their very best, which is pretty damn good.
