I want to point out that any U47 with an original M7 does not sound as a U47 should sound. Those capsules are HIGHLY unstable, and any 30 to 50 year old M7 is not going to have the response that it was intended to. Some of them ripen into a beautiful sound capsule, and some wind up shitty, but they do not sound as intended. They change drastically, and I can't emphasize that more strongly.
I'm not sold on any current production M7s, at the moment. I have a Berlin M7 here that was reskinnned by MTG, and I'm completely underwhelmed.
I think the only way to tell what a U47 SHOULD sound like is with a K47. But that's just my opinion.