US customs won't care if they find new electronics, so they're no problem (they are annoying, with the suitcase thing at port-of-entry, but no problem). As for German customs, I don't know, but: do the initial leave out of Germany over the road where there's checks only in theory and leave from an airport not too far over the border. You can probably get a cheaper flight in the process (e.g. Fly from Basel)