Realistically, living in Manhattan as we do, we're likely to bug-in, since evacuating the island is hard enough on a Friday evening, let alone in a chaotic mass evacuation.
Ha! Truer words were never spoken!
We'd bug out on foot only if we had to abandon our vehicle, which suggests a fairly high threat environment. Under those circumstances, we're assuming a non-permissive environment, so I care less about being low-profile.
Certainly, in that case, anything goes. And I also think most other people would be considered about their own keisters to worry about what others around them are carrying.
I think, unfortunately, if NYers have to bug out, it would almost
have to be on foot as I can't imagine our tunnels and bridges would be able to handle such an exodus. As you said, Friday nights are bad enough.
Cheers!