Does the width of the ribbon affect sound

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.

The area of the ribbon can affect the optimum frequency range of that driver. But "subdued" is strange; sounds like it's not exactly the same impedance as the old one. It will change slightly with time, but it wouldn't jump say 5db in spl...