After my last post, things at Small Archive improved: the archivist made some phone calls and arranged for me to have access to the manuscript for a third day; I got useful work done (involving some modest but real research surprises); and on my last day I encountered, quite by accident, someone who was thrilled to have me there.
I was sitting looking at the manuscript in a spare librarian's office (the special collections room being used for other things, including storage), when someone came through looking for the librarian.
"Oh!" He said, encountering me instead. "Hello! I see you're looking at one of our treasures!"
Oh, um, yeah. I said.
He introduced himself as a historian who sits on a board that advises Small Archive. When he heard what I was doing, he invited me to lunch, introduced me around, and showed me a few local sights associated with the author of the manuscript--who has an important connection to institution that houses the archive.
As I left, he asked to be kept in the loop once the edition comes out, as the institution would love to host a celebration.
So yes, as several of the comments to my last post noted: there are advantages as well as hassles to working at less research-oriented archives.