I wonder whether the geometry will still feel odd after a few shaves. Does the shortened blade allow for east - west passes under the jaw line and the neck like with a DE, or is that still tricky?

I haven’t tried that, but even with a DE, I don’t do east -west passes there (my hair grows not very north -south in this region). I would assume that you if you can do it with a DE, it should be possible with the Barbarossa (it has roughly the same length as a DE blade).

Edit: I guess you’re right wrt the shortened 41.