Thank you for your comments, and particularly for the observation regarding the J seats. For some reason I was under the impression that the seatwells on the 747-8i were slightly bigger in the non-bulkhead rows - but apparently not. If that is the case, I'll probably go with MUC and the 2hr connection. We are on the UD of the 747-8i for our outbound flight.
I would go with MUC.
I'm a big 747 fan, but I have a stricter tolerance for short connections when connecting
to an important segment, just because the magnitude of problem is bigger if you misconnect. 1h00 is fine for that connection on a good day, but it becomes pretty dicey if literally anything goes wrong. There is also the secondary document check for the USA which tends to slow things down a little bit more too.