Truthfully, if I don't find a container of some kind, I didn't find a geocache. I found a Munzee like game QR code for smartphone users, but not a geocache.
I don't much like the idea of a nano either, but the ones that I have already tested in the field have a long life span.
I don't see how a BIT cache inside a camo Altoids tin clearly marked OpenCaching would confuse most geocachers, but I'm sure someone around here would prop it up with a nice new log sheet.
Anyway, I'm just tossing out these questions trying to figure what would work better on Historical Markers. I always enjoyed Waymarking them, and now that I can upload my photos to the cache page here, I plan on listing a few. Thing about many of these Historical Markers, most are going to have a GS cache somewhere in the area.